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By Yasuo Iizuka

We have had studied CO oxidation on unsupported Au powder (mean particle size, ca.100nm) manufactured by evaporating ultra high purity gold metal (>99.99%) in inert gas and reported that it showed some activity after oxidizing pretreatment in O2 at 423 K?453 K. However, recent XPS analysis of the Au powder revealed that it contains much amount of impurity metals such as Ag and In at levels which far exceed those expected from the impurity level of raw gold metal in the bulk. Several samples of Au powder containing different amount of impurity metals were prepared to examine whether the activity depends upon the existence of surface impurity or not. Activity measurements were performed at 273 K after undergoing the powder under various pretreatment conditions. Although the activity of Au powder varied to some extent according to the pretreatment condition, it is strongly correlated to the surface concentration of Ag. Such dependence was not found for In, indicating that the activity of unsupported Au powder is mainly due to the existence of Ag in the surface layer. The activity attributable to ?particle size effect? was not recognized for Au powder with a mean particle size larger than 80 nm.

Oct 1, 2003

By Ruan Chi, Zhenyue Zhang, Zhengyan He

In order to understand what governs the leaching of exchangeable rare earth (RE) and impurities and enhance the RE leaching process, the effects of the concentration of ammonium sulfate, pH and leaching temperature on the migration of RE and aluminum (Al) during the leaching of weathered crust elution-deposited rare earth ore was studied. The elution curves for ammonium ion (NH4 +) were also studied to reduce the consumption of the leaching agent. It was found that a high concentration of leaching agent can enhance the leaching process of RE and Al, reduce the breakthrough volume of NH4 + and more rapidly obtain the equilibrium of NH4 +. However, excessive leaching agent can both increase the cost and the burden on the environment. There is almost no variation on the elution curves of RE and Al in the pH range of 4-8 and control of the pH of the leaching agent can be omitted. It is better for the leaching work to be done in summer since higher temperatures can enhance the RE leaching process and improve the use ratio of ammonium. Using 0.1 mol/L ammonium sulfate for leaching 250 g RE ore, 95.42% RE extraction can be obtained when the volume of leachate is 102.6 mL. At this moment, only 18.17% of NH4 + is used to exchange RE and 49.22% of NH4 + is left in the leachate that can be reused as leaching agent by replenishing ammonium sulfate. The results of our studies can provide theoretical guidance for high efficiency and low consumption exploitation of RE ores.

Jan 1, 2016

"NI 43-101 is a rule that governs how issuers disclose scientific and technical information about mineral projects to the public in Canada. The disclosure standards apply to oral statements as well as written documents and websites. NI 43-101 does not apply to disclosure concerning petroleum, natural gas, bituminous sands or shales, groundwater, or coal be methane. NI 43-101 first came into force on Feb. 1, 2001 and was revised in December 30, 2005. As a “National Instrument”, the law has been passed in each provincial and territorial legislature across Canada.“PART 1 DEFINITIONS AND INTERPRETATION 1.1 Definitions - In this Instrument “adjacent property” means a property(a) in which the issuer does not have an interest;(b) that has a boundary reasonablyproximate to the propertybeing reported on; and (c) that has geological characteristics similar to those of the property being reported on; “data verification” means the process of confirming that data has been generated withproper procedures, has been accurately transcribed from the original source and is suitable to be used; “development property” means a property that is being prepared for mineral production and for which economic viability has been demonstrated by a feasibility study; “disclosure” means any oralstatement orwritten disclosure made by oron behalf of an issuer and intended to be, orreasonablylikely to be, made available to the public in a jurisdiction of Canada, whether or not filed under securitieslegislation, but does not include written disclosure that is made available to the public only by reason of having been filed with a government or agencyof government pursuant to a requirement of lawother than securities legislation; “early stage exploration property” means a property that has(a) no current mineral resources or mineral reserves defined; and (b) no drilling or trenching proposed; in a technical report being filed in a local jurisdiction; “exploration information” means geological, geophysical, geochemical, sampling, drilling, trenching, analytical testing,assaying, mineralogical, metallurgical and other similar information concerning a particular property that is derived fromactivities undertaken to locate, investigate, define or delineate a mineral prospect or mineral deposit; “feasibility study” means a comprehensive studyof a mineral deposit in which all geological, engineering, legal,operating, economic, social, environmental and other relevant factors are considered in sufficient detail that it could reasonably serve as the basis for a final decision by a financial institution to finance the development of the deposit for mineral production; “historical estimate” means an estimate of mineral resources or mineral reserves prepared prior to February 1, 2001;“IMMM Reporting Code” means the classification system and definitions of mineral resources and mineral reservesapproved by The Institution of Materials, Minerals, and Mining in the United Kingdom, as amended; “JORC Code”means the Australasian Code for Reporting of Mineral Resources and Ore Reserves prepared by the Joint Ore Reserves Committee of the Australasian Institute of Mining and Metallurgy, Australian Institute ofGeoscientists and Mineral Council of Australia, as amended; “mineral project” means any exploration, development or production activity, including a royalty interest or similarinterest in these activities, in respect of diamonds, natural solid inorganic material, or natural solid fossilized organic material including base and precious metals, coal, and industrial minerals;"

Jan 1, 2003

By Y. Obara, A. Sato

"Limestone is one of the most important mineral resources, and in Japan it is only one mineral which can be fully supplied by the domestic product. Generally limestone mines in Japan located at mountainous regions, and the combination between bench-cut method and the carry-out system using vertical shaft is widely used in the domestic mines. During mining operations, the occurrence of the blockage in the vertical shafts is very serious problem. Once the blockage in the shafts is occurred, a lot of works and dangerous procedures are necessary to solve the problems. It is thought that blockage is influenced by the cohesion and friction coefficient due to clay minerals thrown into the vertical shafts, however, the quantitative and precise reason is not revealed yet.In this study, the process of blockage occurrence was simulated by 2-Dimensional Discrete Element Method (DEM). In the 2D-DEM analysis, discontinuous circular particles are generated, and the individual movement of each particle is calculated by forward difference method. In the analysis, several typical ore distributions are applied, and the DEM analysis was conducted under the various combinations of cohesion and friction coefficient. From analytical results, it was found that the friction coefficient strongly influences to the occurrence of blockage and there were a threshold values which blockage does not occur. Several kinds of shaft shape were also simulated towards different ore size distributions, and those influences to the blockage occurrence were also discussed."

Jan 1, 2015

By S. Torizuka, I. Mizushima. Kawasakitohri, A. Ohmori, K. Nagai

Strain (work)-hardening in tensile tests were examined for low carbon steels with various ferrite grain sizes ranged from 0.4µm to 16µm. The steels had microstructures composed of ferrite grains and dispersed cementite particles. They were fabricated through warm caliber rolling with an accumulative area reduction of 93%. Strain-hardening rate at a given strain increased with an increase in volume fraction of cementite particles. The balance of yield strength and uniform elongation for ultrafine-grained structures could be improved by the dispersion of cementite particles. Effects of the cementite dispersion and the ferrite grain size on the strain-hardening rate can be roughly explained by the work-hardening model with GN-dislocation density. Strain-hardening design using dispersed cementites was proved to be effective in controlling ductility of the ultrafine-grained steels.

Jan 1, 2004

By M. J. Gagnon

The agglomeration of particulate materials is used in many mineral processes to enhance the settling of the fine particles, Depending upon many physical and chemical parameters, the aggregates demonstrate specific density-size distributions, In this study, a fractal model of the agglomeration process is introduced, Based on reliable experimental data and on physical calculation, the model presented helps to envisage the initial formation of the micro-flocs, and to interpret the subsequent interactions between the aggregates in terms of either coagulation or flocculation, Data from different sources, materials and different agglomeration processes are analysed and compared in the light of the proposed model.

Jan 1, 2005

By M. Sukhram

This paper presents a technique to determine the direction of velocity in liquid aluminum (Al) by measuring the temperature distribution within a cylindrical rod while it is inserted into the flow. The heating pattern of the rod is a result of the interaction of the thermal fields of the rod with the liquid Al. This interaction freezes aluminum onto the cylinder in a characteristic pattern and as a result the temperature response within the rod also follows a distinctive heating pattern. Monitoring the temperature within the cylindrical rod as a function of spatial and temporal coordinates, the direction of velocity can be inferred. Experimental research work involving liquid Al was conducted at the University of Toronto using the Revolving Liquid Metal Tank (RLMT). The RLMT is a resistance furnace which can hold up to 50kg of liquid Al. In this RLMT tangential velocities up to 0.35m1s can be generated. Experimental data for different superheat and magnitude of velocity demonstrate that the sensor records different heating patterns under different fluid flow conditions. Using the transient temperature information, the direction of velocity of the molten Al flow field can be detected.

Jan 1, 2011

By G. Shen, W. R. Tyson

In most fracture toughness test standards, such as ASTM E 1290 and BS 7448, crack-tip opening displacement (CTOD) is measured by using three-point bend (SE(B)) or compact (C(T)) samples with deep cracks. The loading mode and crack depth in these tests sometimes are different from that of pipelines. Pipelines usually have shallow defects and experience tensile loading when the supporting ground moves. As a result, the CTOD measured by these samples is lower than that of pipeline in tension. Recent researches suggest using single-edge-notch tension (SE(T)) samples to measure fracture toughness for pipelines. In the present study, shallow and deep SE(T) samples under fixed grip loading were analyzed by using the finite element technique. An equation to relate the CTOD to the area of the load/plastic crack mouth opening displacement (CMOD) is proposed. With this equation, the CTOD of a SE(T) sample can be evaluated by measuring the area under the load/plastic CMOD curve of a SE(T) sample.

Jan 1, 2005

By K. Nagai

The Asian projects are now in their second terms after the five-year first terms. Ultrafined-grained steels were developed in lab-scale and/or in practical process. Basic approach has been performed to explore the evolution mechanisms of ultrafine-grained microstructures. There have been investigated two approaches to make the ultrafine grains: the "recrystallization route" and the transformation route. In the "recrystallization" route, heavy deformation at low temperature is necessary for the ultra-refinement. In the transformation route, making the high density of ferrite initiation sites in the deformed austenite, especially of the heavily compressed austenite structures, is essential for the ultra-refinement, and further hindering the ferrite growth is also inevitable to utilize the high initiation rate. Strength and toughness are dramatically improved by the ultra-refinement. Fatigue property is also excellent. The poor uniform elongation can be enhanced by the design of the second phase dispersion. At the same time the application has been also pursued from various viewpoints of engineering to take advantages of the ultrafine-grained steels. Bridge, ship, construction, automobile and other high strength parts are being attempted for the application.

Jan 1, 2004

By Matthew Violot

Vale Canada?s Birchtree Mine, located in Thompson Manitoba, has been experiencing problems with hanging wall / footwall dilution, as well as sloughing off of adjacent stopes and temporary stope block backs. Birchtree Mine is interested in determining how time affects the stability of their open stope blocks. Many factors simultaneously influence open stope stability (rock mass quality, joint condition, stress condition). This makes it challenging to determine the influence of a single parameter such as exposure time or stand-up time. This study focuses on determining the effect of exposure time on open stope dilution and combines stress analysis and empirical based approaches.

Jun 1, 2012

By H. Higuchi

The Sumitomo Metal Mining Company Ltd. (SMM) started to produce electrolytic nickel at the Niihama Nickel Refinery in 1939. In 1992, the conventional matte electrorefining process was converted to the matte chlorine leach electrowinning (MCLE) process, which is currently in practice. SMM has mainly used two kinds of nickel matte as the raw material for the MCLE process. Treatment of new raw materials, which have different impurity contents from the original nickel matte, has become mandatory because of changes in the market. Therefore, the MCLE process has been required to increase its flexibility to treat the different impurity contents in the new raw materials. An increase in the capacity for iron removal is included in such requirements. A new iron removal circuit in the MCLE process, based on a process development study, was recently installed. The iron removal circuit is in operation, and efforts are currently underway to optimize the performance of the circuit by changing the present operating parameters. In addition to the removal of the iron, the application is also expected to improve the nickel recovery. The outline of the new circuit and the current iron balance in the MCLE process are described in this paper, together with the effect of the circuit on iron treatment capacity.

Jan 1, 2006

By Nabeel Khan

Annual oil production from the Canadian Oil Sands in Northern Alberta has been rising for several decades, and more ore and overburden are excavated each year from an increasing number of open pit mines. Overburden meeting certain specifications will be used to dam tailings and fill open pits, but the remaining material must be stored in overburden storage structures (OBSS). Well-designed overburden storage structures are more stable and cost less in the short- and long-term. The purpose of this paper is to explore OBSS designs that will be stable yet economical in the short- and long-term. The geological background of the site is briefly discussed, including the effect of each of the main geologic layers (recently deposited till and muskeg, Clearwater Formation clay shales, McMurray Formation oil sands, and the Devonian limestone) on the slope stability of the OBSS. Cost is considered in the analysis when balancing between minimizing costs (steeper slopes) and acceptable factors of safety (flatter slopes), all the while considering the financial consequences of failure. Potential failure planes are identified and probabilistic analysis is conducted on the critical failure surface. The variations in the factor of safety caused by varying pore water pressure, friction angle, and cohesion, are plotted and discussed.

Jun 1, 2012

By Georges Houlachi, Akram Alfantazi, Maysam Mohammadi

Manganese ions in zinc electrowinning electrolytes form a protective MnO2 layer that ultimately decreases Pb contamination in the zinc product. In this study, the effect of dissolved Mn2+ on the electrochemical performance of Pb, Pb-Ca and composite Pb-MnO2 anodes was investigated. The properties of the MnO2 layer formed on these anodes were studied and compared. Potentiodynamic polarization and cyclic voltammetry experiments were performed in 180 g L-1 sulphuric acid to study the electrochemical reactions occurring on the anodes. The anodes were subjected to galvanostatic polarization at 50 mA cm-2. The morphology and uniformity of the MnO2 layer on the anodes were examined using scanning electron microscopy (SEM). Experimental results revealed that the MnO2 layer formed on the composite anode was more compact and uniform compared to that formed on the Pb and Pb-Ca anode. It was also observed that the cell mud formation rate, and consequently manganese ions consumption, depended on the anode type. Although initial formation of the MnO2 layer decreased the oxygen evolution overpotential, its growth might negatively affect electrocatalytic activity of the anodes.

Jan 1, 2014

By Y. M. Shneerson, P. V. Zaytsev, I. V. Fomenko, M. A. Pleshkov

A thermodynamic description of the equilibrium in liquid and gas phases under specific conditions of refractory gold pressure oxidation was generated using the HKF theory. The gold behavior was considered at 190-225°C in the presence of 1-100 mg/L of chloride ion, and under oxidationreduction potential (ORP) of +700 to +1030 mV. The calculations show that the predominant form of gold(I) occurrence is [AuOH]° compared to [AuCl2]?. High ORP favors the formation of [AuCl4]? as a predominant form of gold(III). It is noted that this complex is responsible for the gold losses buildup during POX. Laboratory test results for double refractory concentrate POX are shown. The combined negative effect of (i) organic carbon of the concentrate and (ii) dissolved chlorides in POX slurry on gold recovery is demonstrated. The effects of carbonate blending to the POX feed concentrate and incomplete oxidation of sulfides on POX performance were studied. The pilot tests results of continuous pressure oxidation are also shown and generally confirm the laboratory results and theoretic dependencies. A comparison of the experimental data with the results of thermodynamic calculations is made. As a result of current research, an effective process for POX treatment of carbonaceous sulfide concentrates in the presence of chlorides was developed.

Jan 1, 2014

By Claude Gosselin

En 1995, la Compagnie minière Québec Cartier a mis de l'avant un projet de recherche sur la modélisation de l'écoulement des gaz pour ses fours de frittage à l'usine de bouletage de Port-Cartier. Cette démarche s'inscrivait dans un large processus de collaboration avec l'Université Laval et le Consortium de Recherche Minérale (COREM). L'usine de bouletage possède deux fours de frittage d'une capacité moyenne de 600 tonnes/heure pour chacun des fours. Les fours de frittage sont des systèmes complexes d'échange de chaleur qui fonctionnent à contre-courant (le débit de boulettes versus les débits de gaz). Pour rencontrer les spécifications reliées aux propriétés mécaniques des boulettes, le processus de fabrication requiert des mesures et un contrôle des systèmes très précis. L'information fournie par plus de 70 capteurs (pression, température, puissance, vitesse, hauteur de lit, position de volet....) est utilisée pour manipuler une vitesse de grille, cinq ventilateurs et neuf zones de brûleurs. Malheureusement, les variables qui influencent fortement les mécanismes de frittage, c'est-à-dire les débits de gaz dans les différentes zones du four ainsi que la masse de boulettes qui circulent ne sont pas mesurées. Une méthode est donc proposée pour une estimation en ligne de ces variables. La méthode est basée sur un arrangement de 65 équations reliant pressions, températures et débits de gaz dans les conduites, les ventilateurs, les sections du lit et les fuites (Gosselin, 1998). Pour des raisons de simplification de cet article, seul un sous-système du four sera présenté. Les techniques de réconciliation des données reliées à la conservation de la matière et de l'énergie montrent que la mesure en ligne du débit de boulettes mène à l'estimation des débits de gaz et apporte des avantages intéressants pour le contrôle des variables stratégiques des fours.

May 1, 2001

By S. M. Fatemi-Varzaneh

The AZ31 magnesium alloy is considered as a promising alloy in various applications and industries. Furthermore, to design a proper hot working process (rolling, forging and extrusion), the assessment of hot working behaviour of the alloy is necessitated. Accordingly, the hot deformation behaviour of AZ31 alloy was studied through hot compression testing method. The latter was carried out in a wide range of temperature (523 K to 783 K) and strain rates. The obtained true stress-true strain curves and final microstructures were examined and a partial melting was realized at 740 K. It was concluded that the presence of liquid did change the deformation mechanisms thereby affecting the flow behaviour.

Jan 1, 2005

By D. Y. Li, C. D. Ma, T. Zhou, T. J. Cheng

In this paper, a number of experimental tests are carried out to study the strength difference on rectangular prismatic marble specimens with different height-to-width (H/W) rations. The specimens have a nominal size of 45×15 mm in the compressive cross-section (W×T) and different heights (H = 22.5 mm, 45 mm, 60 mm and 90 mm). It is to say that the height-to-width ratios are equal to 0.5, 1.0, 1.33 and 2.0, respectively. The quasi-static uniaxial compressive tests are finished by a servo-controlled INSTRON machine (the strain rate at about 10-5/s), and the dynamic compressive tests are finished by a diameter of 50 mm cylindrical SHPB apparatus (the strain rate reaching about 101/s). The rock failure process of marble specimens is captured by a high speed camera in order to distinguish the fracture propagation behaviour. It is found that the compressive strengths increase when the H/W ratio of marble specimen changes from 2.0 to 1.0 due to the end clamping effect both for quasi-static and dynamic loads. However, when the H/W ratio changes from 1.0 to 0.5, the apparent compressive strengths decrease both for the two loading conditions. The strength decrease of short marble specimens may be attributed to the change of failure mode from shear to slabbing, which can be identified by the fracture patterns of the specimens. Based on the uniaxial compressive tests, the slabbing strength of the marble was found to be about 40% of its UCS for the specimens with a nominal height-to-width ratio of 2.0. In addition, it is found that the dynamic increase factors (DIF) are affected by the specimen’s aspect ratios. It implies that the same aspect ratios should be used to compare the dynamic and static compressive strength of rocks. Meanwhile, both the static and dynamic tensile strengths of the marble are obtained by the Brazilian disc tests. The ratio of the dynamic tensile strength to the static tensile strength of the marble is about 2.68.

Jan 1, 2015

By John Porritt, Alain Dorval

"TioMin Resources Inc. is evaluating the feasibility of exploiting the heavy mineral sands deposit at Natashquan on the north shore of the Gulf of St-Lawrence, Quebec. TioMin holds the exploration rights to 180 square kilometres, on which 1.6 billion tonnes of sands grading approximately 6% heavy minerals were outlined. The heavy minerals of value include magnetite, ilmenite/hematite, garnet, and zircon. An important part of this evaluation is the development and testing of a mineral separation flowsheet. Under a comprehensive mandate from TioMin, the Centre de recherches minerales (CRM) provided technical assistance to build and operate an on site primary concentrator pilot plant. This plant produced a 93 tonne concentrate, providing over 60 % heavy minerals. This concentrate was shipped to the CRM pilot plant in Quebec City. It was used for further flowsheet testing and for preparation of products and concentrates of heavy minerals with regard to marketing possibilities. This paper presents the flowsheet developed to produce these concentrates.IntroductionIn late 1992, an 11 tonne bulk sample of sand was collected from within the mineralized zone of the Natashquan deposit. This sample was processed over conventional spirals and wet tables at the pilot plant facilities of the Centre de recherches minerales (CRM) in Quebec City. A primary concentrate was produced, from which several 20 kg samples were forwarded to five research laboratories in North America and in Australia. Their tasks were to determine the mineralogical composition of this concentrate and the potential for recovery of marketable minerals from the heavy mineral sands. Satisfactory results obtained from this approach encouraged TioMin to proceed with a more detailed pilot plant program."

Jan 1, 1995

By K. Barbetti, J. Avraamides

"The processing of gold ores with high silver contents can provide operational challenges, such as high cyanide consumption, retardation of gold leaching and competition during adsorption stages of carbon-in-pulp/leach/column (CIP/CIL/CIC) circuits. In particular, the silver, which is about 1.5% of the value of gold, competes with gold during carbon adsorption due to its higher concentration in many Ag-Au ores, potentially leading to gold solution losses. Fresh and partially fouled (barren and regenerated) activated carbons were evaluated at various Ag:Au ratios and total metal concentrations with regard to the adsorption kinetics and equilibrium loadings. Conventional Freundlich isotherms were found to be highly inaccurate for predicting equilibrium loadings in the competitive adsorption environment. An integrated model, which incorporates competitive adsorption kinetics with a modified competitive adsorption isotherm model has been developed and validated using plant and laboratory data. The model performance and some of its salient features will be discussed.INTRODUCTIONThe processing of gold ores with high silver contents can present a range of operational challenges, such as high cyanide consumption, retardation of gold leaching and competition in carbon adsorption circuits. Silver is often present at significantly higher concentrations than gold in many gold-silver ores and competes with gold in carbon adsorption circuits, limiting the gold loading rate and capacity, resulting in gold solution losses and reduced gold recovery.Curtin University’s Gold Technology Group has evaluated fresh and partially fouled (barren and regenerated) activated carbons at various Ag:Au ratios and total metal concentrations to determine the adsorption kinetics and equilibrium loadings for gold and silver. Conventional Freundlich isotherms were found to be highly inaccurate for predicting equilibrium loadings in the presence of both gold and silver.An integrated model, which incorporates competitive adsorption kinetics with a modified competitive adsorption isotherm model has been developed and validated using plant and laboratory data. This paper describes the model performance and some of its salient features."

Jan 1, 2016

By H. Kroog

"This contribution reports recent mineral sorting experience and lists the possibilities of the newest generation of automatic mineral sorters with a special focus on electromagnetic detection, optoelectronic technology and the latest innovative X- Ray transmission units. In industry, mineral and ore are still hand-picked and current automation potential is only utilised in a handful of specific applications. Recently a number of technological developments took place that may increase sorting potential, save mill costs and lead to lower overall tonnage costs. The mentioned technologies provide automatic dry separation of minerals and rock as an alternative for conventional processing. The MikroSort technology is environmentally friendly:•,The remaining waste is free of contaminations•,The dump volume is reduced•,The concentration of the high grade material•,at an early stage saves resources"

Jan 1, 2005