Search Documents

By Ahmad Ghahremaninezhad, Denver H. Cowan

Much of today’s gold is locked within sulphide minerals. These sulphide minerals, including pyrite, need to be subjected to oxidative pre-treatment in order to leach the refractory-gold using traditional methods. Typically autoclaves employing high temperatures between 180?225 ºC, and extremely high pressures between 1,500?3,200 kPa, are used for the oxidative pre-treatment. However, the autoclaves themselves are very expensive, costly to operate and maintain, and produce excess sulphuric acid. This paper studies the atmospheric oxidation of pyrite in ferric sulphate solutions. In general, pyrite oxidation under atmospheric pressure can result in high elemental sulphur production, i.e. less acid generation. Activated carbon has displayed an ability to catalyze the process, achieving reasonable kinetics. The reaction kinetics were investigated by altering acidity of the leaching solution, temperature, catalyst ratio, sparged oxygen and agitation. A combination of X-ray diffraction, scanning electron microscopy, optical microscopy, X-ray fluorescence, inductively coupled plasma mass spectrometry (ICP-MS), and atomic absorption spectroscopy (AAS) were used to monitor the kinetics of the process and elemental sulphur yield. The purpose of this investigation was to determine optimal operating conditions that maximized kinetics of the atmospheric oxidation while maximizing elemental sulphur yield.

Jan 1, 2015

By Z. Ren, M. Tomlinson, E. Asselin

"Organic carbon blinding is a common, yet often partial, solution to the reduction of preg-robbing. A quantitative method to assess the extent of adsorption of a given blinding agent is presented herein. The adsorption of several blinding reagents on various carbon samples is quantified using electrochemical impedance spectroscopy (EIS). EIS results showed that kerosene is more strongly adsorbed on carbon than sodium lauryl sulphate (SLS), while SLS can hinder the charge transfer process of the oxygen reduction reaction on the carbon surface more effectively. The effectiveness of SLS is pronounced when its concentration is higher than 100 ppm. Raman spectra are presented for selected carbon samples: as the area ratio of the disordered peak to the graphitic peak increases, blinding agent adsorption increases.INTRODUCTION The presence of naturally occurring constituents in gold ores may adversely affect the extraction of gold in cyanide leaching since the gold cyanide complex, Au(CN)2–, can be adsorbed by these constituents (M. Adams & Fleming, 1989; Afenya, 1991; Miller, Wan, & Díaz, 2005). Such ores are known as “preg-robbing”. Preg-robbing behavior may arise from natural carbonaceous materials in the ore (M. Adams & Burger, 1998). In the past decades, a number of pre-treating methods have been developed for refractory carbonaceous ores (Arriagada & Osseo-Asare, 1984; Beer, 1994; Dunne et al., 2007; Jiang, Liu, Xiao, & Yang, 2012; Kohr, 1997; Kulpa & Brierley, 1993; Menne, 1992; Menne & Revy, 1994; Moyes & Houllis, 2010; Petrie, Craw, & Ryan, 2005; Simmons, 1996). The method known as blinding is one of the most effective and economical pre-treatment methods (M. D. Adams & Burger, 1998; Albert, 1923; Darrow, 1924; McQuiston & Shoemaker, 1975; Van den Berg, 2000). Blinding, also referred to as blanking or passivation, uses a chemical reagent to passivate the preg-robbing carbon by selective absorption or wetting (Bas, Altinkaya, Yazici, & Deveci, 2012; Brierley & Kulpa Jr, 1993; Dunne et al., 2012; Van den Berg, 2000; Yang, Qian, Song, & Dong, 2013; Yen, Amankwah, & Choi, 2008; Zhou, Jiang, & Choi, 2014). Organic reagents, which selectively adsorb on the surfaces of activated carbon and “smother” the surface, have been used for blinding carbonaceous matter in gold ores prior to cyanidation. Two comprehensive studies by Abotsi and Osseo-Asare and Adams and Burger have been published on this topic (Abotsi & Osseo-Asare, 1986; M. D. Adams & Burger, 1998)."

Jan 1, 2017

By John D. Galloway

Mining is one of the important primary industries of Canada, with a gross production in 1927 estimated at $241,773,000- the highest in the history of the country-and an impressive dividend record. It is quite apparent, therefore, that mining is a business worthy of the careful attention of the people of Canada. Furthermore, with a vast undeveloped territory more or less mineralized, it is highly probable that our mining industry will continue to expand indefinitely, with a consequent increase in production and in the amounts of the yearly profits distributed. In recent years, the public has taken a larger interest than formerly in mining-an interest, moreover, that is not academic, but primarily from the viewpoint of profits. It is quite evident that mining is a profitable business, at least to some, and the average man on the street, hearing of these profits, is attracted thereto. I have no doubt that many of you have .read in promotion prospectuses, with figures to prove it, that mining is the most conservative, the safest, and the highest-yielding business in the world. Now, a lot of this information is best judged by the old saying that "While figures don't lie, liars figure". At the same time, mining, properly conducted, is a profitable business, even though speculative, and undoubtedly much profit will come from Canadian mines in the future. In this paper my conclusions regarding mining investments are based largely on British Columbia experience, together with some slight knowledge of mining conditions in the other Provinces. It is considered, however, that the inferences drawn are applicable to mining throughout Canada.

Jan 1, 1928

By J. Lammers, D. Adams

Most pressure oxidation operations introduce oxygen through a large multi-use nozzle in the vapour space of the autoclave. Sparge pipes extend inside the vessel to the point of discharge below the compartment agitator. However, two zinc pressure leach operations have successfully used a bottom entry oxygen sparge system for a number of years. Recently, the concept has been used in a whole ore gold pressure oxidation operation as well as a copper pressure leach plant. Both of the latter operations also introduce cooling water for temperature control through the same sparge pipe. This paper addresses the benefits of the bottom entry system with regards to autoclave performance and the positive effects on agitator performance.

Jan 1, 2004

By D. F. Zhang, X. Q. Jiang, N. Tahreen, D. L. Chen, F. S. Pan, D. Y. Li

Alloying with rare-earth elements has been proven to be an important tool for magnesium to achieve superior properties via texture randomization. The role of yttrium in texture weakening and the link between texture and formability are fairly well known. Since annealing is a vital part of metal processing which could significantly contribute to ductility, it is important to ascertain the impact of annealing in terms of texture change. Also, an understanding about texture development during pre- and post-deformation annealing is essential to improve the industrial deformation processing as texture is closely related to formability. While there is independent information in the literature regarding the effect of rare-earth addition and heat treatment on the texture formation, no systematic studies have been reported on the collective impact of yttrium addition, annealing and deformation on texture evolution. The present study was, therefore, aimed to identify the inter-relationship among texture evolution, yttrium content, heat treatment and deformation behavior in an extruded Mg-Zn-Mn-Y alloy. Annealing at 450°C for 1 hour and uniaxial compression tests at a certain amount of deformation were performed. The deformed and annealed samples were then subjected to annealing and compression test, respectively, followed by texture measurements. It was observed that yttrium addition effectively weakened the crystallographic texture in all conditions, which was evident from the changes in the microstructures and textures.

Jan 1, 2015

By W. A. MacDonald, C. M. McGibbon, J. H. Reynolds

This paper traces the development of the Seaboard Power Plant, which plays such an important role in the industrial life of Nova Scotia. It also shows the involvement of the plant in the siting of a heavy water production facility in Cape Breton. The paper concludes with an outline of the new installations which the Nova Scotia Power Commission has undertaken as an extension to the Seaboard Plant.

Jan 1, 1966

By C. W. Drake, J. H. Walsh

"The Canadian Carbonization Re-search Association was formed during 1965, with seven founding members representing four integrated steel companies, two coal companies and one high-temperature tar processing company. The purpose of this paper is to review the circumstances which led to the formation of this new research association and to discuss its general objectives. Also discussed will be the organization of the Association, the nature of its relationship with the Department of Energy, Mines and Resources in the early stages, and some of the technical programs which have now been initiated."

Jan 1, 1967

By Eduardo R. Rodrigues, Ankur Narang, Roberto Federico Ausas, U. T. Mello, Jose Maria Segura Serra, M. R. Lakshmikantha, Ignacio Carol, Kamal C. Das

"Modeling of big faults or weak planes of strong and weak discontinuities is of major importance to assess the Geomechanical behaviour of mining/civil tunnel, reservoirs etc. For modelling fractures in Geomechanics, prior art has been limited to Interface Elements which suffer from numerical instability and where faults are required to be aligned with element edges. In this paper, we consider comparative study on finite elements for capturing strong discontinuities by means of elemental (EFEM) and nodal enrichments (XFEM) for Geomechanical applications. For general fracture scenarios, Oliver et al. (2008) have demonstrated advantages of EFEM over XFEM for including: (a) ease of modeling in any standard finite element code due to the possibility of static condensation, (b) higher accuracy in some cases for coarse meshes, and, (c) a reduced computational cost. However, there has been no work that considers cohesive fractures in Geomechanics. We present a numerical analysis based on a linear constitutive model and linear triangular elements for the bulk and a linear constitutive behaviour for the fault for a representative set of fault planes in a circular tunnel made in rock mass. In the numerical examples we consider both well-traced and bad-traced meshes. We focus on traction profile analysis for both EFEM and XFEM, since that is crucial to understand the cohesive fracture behaviour specially rock joint. Therefore in each case, shear, normal and stress ratio are compared across the two methods along the fault plane. This is the first such work that compares XFEM and EFEM behaviour for Geomechanics problems.For the considered class of problems and the sharp penalization approach without regularizations adopted, it can be observed that accuracy and robustness of EFEM may strongly depend on the fault orientation with respect to the element edges, while, XFEM is independent of fault alignment with element edges. It has been also observed that, with mesh refinement model, stress oscillation completely removed with XFEM however EFEM fails to provide oscillation free results with finer mesh in case bad-traced model. We also performed error analysis and found that in case of bad-traced mesh the average error in the XFEM is 84% smaller than of EFEM and for XFEM the error goes to zero with increasing mesh resolution, while for EFEM the error increases with mesh resolution. Thus, we experimentally demonstrate that, XFEM performs better than EFEM in terms of accuracy and rate of convergence with marginal increase in computational cost. This work hence provides novel insights on the application of XFEM and EFEM in Geomechanics."

Jan 1, 2015

Presentation Outline ERM ? corporate profile Background to sustainability reporting GRI G3 Guidelines (Oct 2006) Best practice examples Contact information ERM ? corporate profile Over 35 years of experience World?s largest all-environmental consultancy* 130+ offices in 40+ countries; 3,200+ professional staff Worked with >50% of the Global Fortune 500 (FY07) Annual turnover > US$500 M (FY07) 2008 Environmental Advisor of Year** Offices/Staff ? Canada (5/50) and US (65/1,350) *Source: Engineering News Record: July 2, 2007 ** Source: Acquisitions Monthly: December 2007

May 1, 2008

By Dr. Ralph W. Edie

The limestone reef reservoir at Swan Hills consists essentially of a "buildup" of successively smaller atoll-like layers. Precipitation of calcium carbonate within the lagoonal area of each layer essentially kept pace with growth of the outer organic lattice. Within the reef mass, six de-positional environments characterized by specific suites of fossils (or fossil fragments) and associated limestone textures are recognized as follows: ( 1) Aerated moderately agitated water of normal marine salinity (widespread shelf or submerged reef-built platform). Thamnopora-type corals, Amphipora, "pancake" stroma-toporoids, crinoids, articulate bra-chiopods, rare rugose cup corals, and ostracods occurs in light gray-buff skeletal microgranular limestone of low permeability. (2) Semi-stagnant quiet water of normal marine salinity (leeward side of reef). Crinoids, articulate brachio-pods, rare thamnopora-type corals, Amphipora, pancake and bulbous stromatoporoids, rugose cup corals, ostracods and gastropods occur in impermeable dark brown argillaceous skeletal calcilutite with thin black bituminous shale beds and rare dark chert nodules.

Jan 1, 1961

By P. Babak, E. Insalaco, O. Babak, P. Henriquel

"Detection of outliers is an important primary step in geomodelling. Geological datasets often contain errors due to problems such as measurement device limitations and recording glitches. In this paper, a robust Mahalanobis distance–based approach is successfully applied to particle size distributions of the Joslyn lease, an oil sands development site near Fort McMurray, Alberta, Canada. Automatic outlier detection and geological review were combined. Outliers from the Mahalanobis distance approach were compared with their respective core photographs to determine if laboratory measurements and facies classification were correct. A checking procedure for laboratory technicians is proposed.RÉSUMÉ La détection des valeurs aberrantes constitue une étape primaire importante de la modélisation géologique. Les ensembles de données géologiques contiennent souvent des erreurs en raison de problèmes tels que les limitations des instruments de mesure et des pépins d’enregistrement. Dans le présent article, une méthode robuste basée sur la distance de Mahalanobis a été mise en oeuvre avec succès aux granulométries du bail minier Joslyn, un site de sables bitumineux en développement à proximité de Fort McMurray, Alberta, Canada. La détection automatique des valeurs aberrantes a été combinée à une étude géologique. Les valeurs aberrantes de la méthode de la distance de Manalanobis ont été comparées avec leurs photographies respectives de carottes de forage afin de déterminer si les mesures en laboratoire et la classification des faciès étaient correctes. Une procédure de vérification pour les techniciens de laboratoire est proposée."

Jan 1, 2015

By T. Billotte, G. Tirand, J. Zollinger, V. Robin, B. Rouat, D. Daloz

The grain structure prediction of metallic alloys during a welding process is often an issue. In addition to the welding parameters and the alloy nominal composition and properties, the base metal grain structure and chemical homogeneity also play an important role in the formation of the final microstructure. In this paper intensive characterisation of solidification structure in gas tungsten arc welding of Ni base alloy 600 are described. It is shown that in transverse section of the weld, while the grain structure shows some texture following constrained solidification growth, grain density in the weld is similar or greater than grain density in the heat affected zone. This suggests that simulation of the welding structure needs, in order to be predictive, to take into account : epitaxial growth, secondary nucleation events and 3D growth inside the weld pool.

Jan 1, 2015

By Antonius Prayoga

PT Smelting adopted the Mitsubishi Continuous Technology for its copper smelter plant which has been operating since 1998. Through a series of expansion projects, the plant annual production capacity increased gradually from 200,000 to 300,000 tons of copper. There were no significant modifications for the smelter to reach the 50% additional capacity. It was mostly achieved by intensifying the operation of the furnaces by increasing the oxygen content in the furnaces blowing air. Intensive smelting furnace operation caused shorter campaign life of some furnace refractory, especially the melt zone wall on furnace outlet. During each furnace relining, which is done once every two years, severe wall erosion was found. The worst condition occurred in 2007 when the smelting furnace experienced a melt leak through the eroded wall beneath the bath-line coolers. During the 2008 furnace relining, a modification was performed by installing vertical coolers behind the melt zone wall. Additional vertical coolers were installed during the 2012 furnace relining to extend the coverage area. The modification improved melt zone wall integrity significantly by keeping them safely within the two year campaign life. Recently a modeling study was done to estimate the influences of molten waves on furnace wall erosion. The aim of the study was to predict the impact of blowing parameters, such as blowing air velocity, on the melt wave character and wall erosion.

Jan 1, 2015

By A. L. McAllister

"MASSIVE sulphide deposits are found in two areas of New Brunswick, the St. Stephen area and the Bathurst-Newcastle area. In both, the geology in the immediate vicinity of the sulphide bodies is largely inferred from drilling results as outcrop is not plentiful and is, in fact, almost lacking in most places. With few exceptions these deposits have not been explored by underground methods. Consequently much of the. detail on the geology will only become known over a period of years as economic conditions make mining feasible.Much of the information contained in this paper has been supplied directly by company geologists. As a result of the number of contributors, some confusion of nomenclature bas to be anticipated. Cross-sections and plans of the individual deposits are, in most cases, as supplied by the companies concerned. Most of the interpretations are the responsibility of the author."

Jan 1, 1960

The writer presents a concise summary of eleven recent discoveries made in the Maritime Appalachian area, with suggestions for fur the research. This information may prove helpful to geologists working in other fields and to students contemplating further avenues of research in mining geology and exploration. INTRODUCTION THIS paper is not intended as a research study on the subject, but i. merely a brief review of eleven discoveries that have been made in the Canadian Appalachian area. Furthermore, this is not a critical analysis of the merits of any one geophysical method, but it is an un-prejudiced observation of how these discoveries were actually made and what techniques were apparently most fruitful. Some generalizations are attempted whicl1 may suggest further avenues of research in the field of mining exploration. The writer wishes to thank his colleagues in the field for their comments, which he was able to in-corporate into this paper. In particular, he is grateful to Dr. Paul Bevan and

Jan 1, 1963

By G. M. Behrend

"The mining and processing of mineral ores is a very old industry which is steeped in tradition. Rising demand for metals has recently forced the exploitation of lower-grade orebodies which require extensive beneficiation. The high capital expenditures involved, together with market pressures for high-quality concentrates and pellets, have forced the development of new process technologies which are heavily dependent on automatic process control. Development of suitable instrumentation has been rapid and it is being applied to mining processes today with a high degree of sophistication. The drive for higher efficiency and profitability goes on and has reached a level at which modern digital computers appear to be the only answer. However, the efficient application of a digital process computer is extremely complicated and is therefore approached by the mining industry with considerable hesitation.Some of the benefits promised by the digital computer can be obtained today by other means, which are more manageable and can provide immediate payoff. The result would be a building-block system which would utilize the digital process computer as its final component, to perform true plant optimization, free from routine chores."

Jan 1, 1971

By F. A. McLean

Given a promising claim and the required financial backing to develop it, the first problem that confronts the mine operator is usually the selection of the necessary compressed air plant. The size and type of drive are questions that naturally follow, the former being determined largely by the amount of money available and the speed with which it is desired to carry on the programme of development. The type of drive, such as electric motor, steam or oil-engine, depends on local conditions and has an important bearing on the cost of operations. ns. Few prospective mine operators are fortunate enough to locate claims within the service radius of electric power-lines, although this is more likely to happen nowadays than formerly. In the majority of cases, however, some other form of prime mover is necessary. When wood or coal are available at moderate cost, a small steam-driven plant is usually chosen. Such plants are often arranged so that they can be converted to electric-drive should future developments at any time make this desirable. Many plants of this type are installed in northern Ontario mines. When wood or coal are costly or difficult to transport, oil-engine driven mining plants have many advantages in their favor, and are now quite commonly used. Oil in some locali-ties is considerably cheaper than wood or coal, and is much easier to transport over bad roads.

Jan 1, 1924

By F. E. Millett

The following notes deal chiefly with changes from steam to electric drives, or, in the case of the Bellevue pumps, from air to electric. Where electric power can be purchased or generated cheaply it can be used to advantage and is generally more economical than steam, especially in places remote from the central power-plant. Nothing could be more simple than the operation of electrical gear. It does not require a competent engineer constantly on the alert, oiling and watching bearings, and maintenance is at a minimum. The ease with which the current is transmitted from its source to where it must do its work is one of its greatest advantages. Transmission losses are very low. Generally speaking, the smaller the plant the lower the loss and 90 per cent, and better, efficiency is easily attained. In and around Bellevue 2300-volt, three-phase, is the standard distributing pressure; our power requirements and the distances transmitted, for the present, do not require more than this. Most of the heavier motors are 2300-volt .machines, which eliminates the cost and possible troubles of step-down transformers, and makes for a cheaper and less bulky motor. This applies to two fan, two hoist, and two compressor motors, the smallest being 75 and the largest 520 horse power. The standard pressure on power lines to all inside pumps is 550 volts, and 220 volts is general for the the tipple. While 110 volts is used for house and office lighting service, it is not economical around and in the mine. No matter what kind of device is used to lock and protect the lamps, they are invariably missing.

Jan 1, 1926

By F. Rashchi, A. Ghahreman, J. Moghaddam, S. Karimi

"In this work, the kinetics of ferric-ferrous redox reaction on a passivated sphalerite electrode is studied by the application of chronoamperometry method in 0.5 mol L-1 H2SO4 solution. The electrochemical behaviour of ferric and ferrous couple was investigated on two sphalerite minerals acquired from two different geological regions (Iran and Canada). The carbon paste electrode (CPE) of sphalerite was initially prepared and passivated in 0.5 mol L-1 H2SO4 solution and after reaching the steady-state condition, ferric and ferrous sulfate solution was added. The registered current density differences between the current density of the passivated electrode and that of the electrode in the iron salts added solution were interpreted for kinetics of ferric-ferrous reduction-oxidation reaction. The equilibrium potential for ferric-ferrous couple on sphalerites surface was about 500 mV vs. Ag/AgCl. The exchange current density (i0) for ferric-ferrous redox reactions on the sphalerite samples had the same magnitude of 10–6 A cm–2. The electrochemical impedance spectroscopy (EIS) measurements at 550 mV vs. Ag/AgCl illustrated that sphalerite oxidation was controlled by two charge transfer process in both of Fe-free and Fe-containing solutions. The charge transfer resistance remarkably decreased when Fe salts added to the 0.5 mol L-1 H2SO4 solution, owing to the ferric-ferrous redox reactions being the predominant reactions on sphalerite surface.INTRODUCTION Direct atmospheric leaching processes for sphalerite concentrates are performed by reduction of an oxidant (e.g. ferric ion and oxygen) and oxidation of sphalerite to zinc ions. Oxygen could be an oxidizing agent as well, but the concentration of oxygen is very low in the solution. The role of ferric ions is predominate in this oxidation (Babu, Sahu, & Pandey, 2002). The oxidation reaction for sphalerite in the presence of ferric in can be presented as follows (Lampinen, Laari, & Turunen, 2015):"

Jan 1, 2017

By L. Tejeda, J. R. Donald, R. Parra, J. Duran, P. H. Lauzon

"Crucible slag tests were employed to evaluate different refractory brick classes for the Cerro Matoso electric furnace. Comprehensive analysis was conducted to evaluate the crucible erosion and characterize any slag/refractory reaction products.The classes of refractories investigated were:•,tar-impregnated magnesia;•,rebonded fused grain magnesia-chrome;•,direct bonded magnesia-chrome;•,alumina-chrome;•,picrochromite; and•,magnesia-alumina (spinel).It was concluded that tar-impregnated MgO bricks were the most suitable for the slag chemistry and furnace environment according to corrosion and infiltration resistance. A picrochromite (MgCr2O4) brick performed exceptionally well with regards to erosion resistance, however, the slag infiltrated extensively through the brick pores. Alumina-chrome, direct bonded magnesia-chromite, and spinel (magnesia-alumina) bricks were evaluated as not suitable for use in the furnace."

Jan 1, 1999