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By George P. Demopoulos, Amani Al-Othman, Terry C. Cheng

One critical issue in chloride hydrometallurgy is the regeneration of the lixiviant HCl that is currently achieved by pyrohydrolysis. In this paper, a low temperature HCl regeneration process was investigated which regenerates HCl and produces saleable gypsum. This process promises to reduce the generation of wastes by the reaction of spent calcium chloride leach liquors with sulfuric acid solution at low temperature. Experiments were performed to determine the optimum conditions of the reaction in terms of temperature, reagent concentrations, rate of reagent addition, mixing and seeding/recycling to produce marketable gypsum and HCl with practical strength.

Jan 1, 2004

By Michael Schindler

Uranyl mineral dissolution appears to be complex, affected by factors such as solution pH and the presence of various cations in solution, and sometimes involving formation of secondary surface precipitates. Such secondary precipitates potentially could armor the underlying uranyl mineral surfaces from further dissolution. A detailed understanding on the formation of secondary precipitate is therefore essential for predictive modeling of radionuclide fate and transport in the subsurface. Several types of secondary precipitates on the surface of uranyl minerals were examined using Atomic Force Microscopy, Scanning Electron Microscopy, and, Xray Photoelectron Spectroscopy.

Aug 1, 2010

By Simon D. Handelsman, Malcolm Scoble, Marcello Veiga

"Abstract - In many mining areas, potentially profitable mineral projects can be at risk because local people do not trust their governments and mining companies on many issues, including human rights. Projects will continue to be vulnerable to potential failure, delays, and higher costs. This paper suggests that geoscientists need to be aware of the global challenges they face from issues of corporate social responsibility, sustainable development, and human rights. These are not areas in which geoscience education has traditionally focused.This paper examines the types of conflict concerning human rights that are encountered by geoscientists involved in mineral exploration and development. It provides a background to human rights issues and presents a classification of the types of issue encountered. It reports on a survey of case studies that provide examples of the breadth, complexities, and consequences of such issues. The paper then concludes by outlining the development of codes and standards to improve performance, and suggests approaches for positive, practical engagement."

Jan 1, 2003

By B. T. Lu, J. L. Luo, H. X. Guo

This paper investigated the synergistic effect in the slurry-erosion process of carbon steel. In line with the mechanisms of material loss, the synergism due to interaction of erosion and corrosion was divided into the corrosion enhanced by erosion and erosion enhanced by corrosion. The erosion-corrosion tests were conducted with A1045 steel in slurries containing silica sand. Experimental results showed that the rotating of the sample in corrosive media raised both OCP and corrosion rate, but the impingement of solid particles did not affect the corrosion current significantly. In the quiescent solutions, the Faraday's law gave a good prediction for the weight loss caused by corrosion but for rotating samples, the weight loss experimentally measured was virtually greater than that predicted by the Faraday's law, indicating that the corrosion-enhanced erosion could occur in corrosive fluids in absence of solid particles. A half-logarithm relationship was observed between the weight loss due to corrosion-enhanced erosion and the anodic current density.

Jan 1, 2004

By J. A. Hurd

Towards the goal of a better understanding of the structure-proton conductivity relationship in PEM materials, this project concerns the design of ordered polymeric solids containing well-defined sulfonate aggregates. The approach employed involves the templation of sulfonated monomers using core principles of crystal engineering. In addition to sulfonate groups, the monomeric units contain crosslinkable functionalities to enable formation of a covalently linked network. The templation strongly directs the construction of well-defined sulfonate clusters and aggregates. Structural, sorption and conductivity data for the networks will be shown.

Jan 1, 2005

By Katherine (Kate) Bruce

Aurora College ? Yellowknife Campus, in partnership with the Northwest Territories Mine Training Society and industry partners, has developed a 6 ? week program on Underground Mining for delivery in Northern communities. The goal of the program is to inform and connect Northern residents to the career potential at existing and future mining operations throughout the Northwest Territories. The program content includes an introduction to the mine life cycle, basic underground mining methods, the use of technology in training via desktop simulators for underground mining equipment, safety in the workplace, and essential skills training (Ready to Work - North) and assessment. Students completing the short program may then choose to continue into a long (12-week) program to be offered at the Yellowknife Campus. This program expands upon the initial introduction and includes modules on NWT geology, environmental studies, underground mining processes and underground mining equipment operation using the larger enclosed cab simulator for a variety of equipment being used at northern mining operations. Success of both programs will depend upon a variety of factors, many of which are outside of the control of the developers of the training modules. These will be investigated throughout the presentation. Connecting northern employers with northern employees is a major concern. It is hoped that through the development and implementation of a program such as this, that the connection can be made and sustained allowing continued employment for the life of northern mining operations.

May 1, 2008

By Y. Qi

A cell-level nonlinear dynamic model of solid oxide fuel cell (SOFC) based on physical diffusion principles is built in this note. It demonstrates that reactant diffusion processes from gas flow bulks to triple phase boundaries (tpbs) play an important role in the dynamic behaviors of SOFC. The simulation shows that under certain condition, the effect of the double layer capacitance may be neglected. The phenomenon of slow rise of voltage in current interrupt experiment may be explained by the dynamic behaviors of partial pressures in the vicinity immediately above tpbs.

Jan 1, 2005

By A. Chaisantikulwat

Most solid-oxide fuel cell (SOFC) modeling emphasizes steady state cell operation. However, understanding the dynamic behavior is essential to predict the performance and limitations of SOFC power systems. In this work, we demonstrate a dynamic model of a SOFC, and we simulate a feedback control scheme that can maintain output voltage despite load changes. Dynamic response is determined as the solution of coupled partial differential equations derived from conservation laws for energy, mass and electric charge. From such a model, the step responses to system input variables can be determined. Low order dynamic models that are sufficient for feedback control design can be derived from the step responses. The development of the partial differential equation model is outlined, and the limitations of the control system are discussed.

Jan 1, 2005

By Michel Noël

This paper presents a partial compilation of adopted measures of waste rock dump closures at mine sites located in Canada and Alaska, where the climate includes cold winters. The paper also presents the selection process that was followed for some of those mine sites. Mining operations usually generate waste rock that can sometimes result in very large quantities. Additionally, the nature of the ore body and the host rock will often introduce environmental impacts. These impacts need to be managed not only during the operations but also in the long term. Mine closure plans consequently have to address the long term issues that sometimes require perpetual treatment. Closure planning often involves the evaluation of risks associated with environmental and financial liabilities. It needs to consider the science, some common definition of objectives, and there will be a need to manage resources and schedules. Closure planning is essentially an exercise in constrained decision making. A performance and risk based ranking matrix is often developed during this selection process to identify the preferred option(s). The case studies presented in this paper provides a few examples. The level of knowledge on acid rock drainage from waste rock dumps has increased considerably over the past decades. It did not necessarily increase the level of complexity of the adopted closure methods, as the selected closure methods are often kept simple. A common approach consists of stabilising the slopes of the waste rock dumps material by resloping and then covering the waste rock with a growth media to support vegetation. Such covers prevent direct contact of animals with the waste rock material, minimise erosion and reduce infiltration to various degrees. The inclusion of water treatment is obviously dependent on the water quality being released.

Nov 1, 2008

By Michel Noël

Cet article présente une compilation partielle des mesures adoptées pour la fermeture des haldes de stériles pour des mines situées au Canada et en Alaska, et dont le climat comporte des hivers froids. L?article présente également le processus de sélection qui a été suivi pour certaines de ces mines. Les exploitations minières produisent habituellement des quantités de stériles qui peuvent être importantes. De plus, la nature du dépôt minier ainsi que la roche mère vont souvent entraîner des impacts sur l'environnement. Ces impacts doivent être gérés non seulement durant les opérations minières, mais souvent à très long terme après la cessation de l?exploitation minière. Les plans de fermeture de mine doivent par conséquent procurer des solutions à très long terme, voire même à perpétuité dans bien des cas. Le processus de sélection implique souvent l'évaluation des risques liés aux responsabilités environnementales et financières. Il doit considérer l?aspect scientifique, comporter une définition des objectifs, tout en incorporant une gestion des ressources et des plans de travail. La planification de fermeture est essentiellement un exercice de prise de décisions comportant des contraintes. Une matrice de classement basée sur la performance et le risque est souvent développée durant ce procédé pour identifier les options préférées. Les études de cas présentées dans cet article présentent quelques exemples. L?état des connaissances sur le drainage acide minier provenant des haldes de stériles a augmenté considérablement au cours des dernières décennies. Ceci n?a pas nécessairement augmenté le niveau de complexité des méthodes adoptées pour la fermeture. Une approche qui est fréquemment utilisée consiste à stabiliser les pentes des haldes de stériles en abaissant la pente des talus pour ensuite recouvrir les stériles d?une couche de sol pour soutenir la végétation. De telles couvertures empêchent les animaux d?avoir un contact direct avec les stériles, minimisent l'érosion et réduisent l'infiltration à divers degrés. L'inclusion d?un traitement des eaux dépend évidemment de la qualité de l'eau au point de déchargement.

Nov 1, 2008

By M. Amsden

"Since the computer program is far from complete this must be only a brief progress report on the computerization of flotation metallurgy at the Ecstall concentrator at Timmins.Ecstall is currently treating about 10,000 tons per day of two different ore types. One is a low sulphide copper-zinc ore, the other is a high sulphide lead-zinc-silver ore. The concentrator is divided into three individual grinding and flotation circuits. In effect there are three mills under one roof. Normally there are two circuits on copper-zinc ore and oneone lead-zinc-silver ore. At this point in time one of the copper-zinc circuits is under computerized metallurgy control.The first step in this control is the use of an ARL on-stream x-ray analyzer, coupled with a Honeywell 21 computer which types out assays and recoveries for each individual circuit. Our approach to a computer program was to keep it simple. The program was written to coincide as closely as possible to what an operator would do in the performance of his duties based on the in-formation he was getting from the x-ray analyser read-out. Initially, computer control was put on just the copper circuit of the ""A"" Division, controlling the collector addition at three points in the circuit; primary, secondary, and scavengers. The control was based on recoveries and the grade of the copper concentrate. Targets like 95% recovery and 24% copper concentrate grades that it was felt the circuit could achieve were set to start with. It quickly became apparent that this alone was not enough because if on a certain ore the best recovery that could be made was only 94.9% the computer kept calling for more reagents until the circuit was completely out of control. On another ore it might have been quite possible to get 96% recovery but when the set point of 95% was reached the computer stopped trying for any more. To overcome this problem a very simple optimum seeking program was devised by one of the Ecstall staff and it has worked very satisfactorily since being put into use in July 1970.In the copper float only the two collectors R-208 and the xanthate R-317 are under computer control. The addition of frother and depressant is left to the operator. The flotation cells have automatic level controls which can be adjusted by the operator. pH is controlled automatically through a lime loop-sensor arrangement."

Jan 1, 1971

By John S. Stevenson

"Although we have no uranium- producing mines as yet in British Columbia, uranium, associated with gold and cobalt, has been found in two deposits in amounts such that the combined value of the metals not only warrants the further exploration of these deposits, but also encourages the search elsewhere in the Province for other similar deposits.Where uranium-bearing veins have been found in British Columbia, the uranium mineral is the crystalline variety of uranium oxide, uraninite, rather than the massive, non-crystalline variety, pitchblende, such as found in the Great Bear Lake deposit and in other similar deposits along the southwestern margin of the Precambrian shield.The principal occurrences of uranium known so far in British Columbia are associated with bodies of granodiorite and quartz diorite along the eastern side of the Coast Range belt of batholiths. In this part of the Province, interesting amounts of uranium occur on the Gem property in the Bridge River area and on the Victoria property south of Hazelton; and smaller amounts occur on the Red Rose, Rocher Debouze, Delta, and Ohio properties, also south of Hazelton. At the Gem and the Victoria, the uranium mineral, identified as uraninite, occurs in deposits that also contain abundant cobalt-nickel sulpharsenides, and molybdenite.At these properties, the uraninite occurs as clusters of small black crystals of sub-metallic lustre that may be seen upon careful -searching of a highly radioactive specimen with a hand lens. Under the microscope, the uraninite is seen to be in the form of cubes or modifications of cubes that may occur as individual grains widely scattered throughout the gangue or may be gathered into clusters of several grains. The grain size of the uraninite is in general small. Although a few clusters of grains are up to about 10 mesh in diameter, the individual grains, whether in clusters or widely disseminated, are rarely more than 400 mesh in diameter."

Jan 1, 1950