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By W. L. Strand, D. N. Madge

"Experimental and pilot operations in bituminous sand processing require due care and attention in the design and analysis of measurement programs. This paper deals with a case study in experimental design and data analysis for a series of experimental campaigns that have been conducted over the past five years by Kilborn Western Inc., acting on behalf of Bitmin Resources. Beginning with the design of the experiment and following into the use of linear and nonlinear regression models, the phenomenology of bitumen extraction is illustrated. The final testing program tested 13 oil sand types as well as a wide range of process variables for all the unit operations of the complete process.The program was successful in developing process fundamentals and scale-up criteria. Several phenomenological models were proposed and tested. Their range of applicability was explored. This paper illustrates the range of applicability of these models and discusses the development of alternative models.IntroductionOver the past five years Kilborn has conducted a series of bench scale and pilot scale experiments designed to explore the phenomenolgy of a new concept in medium temperature processing of bituminous ores. These experiments at feed rates ranging from .1 to 24 t/h were conducted on water wet sands from the .Athabasca region near Fort McMurray. They were based on experimental designs chosen to provide a systematic means of identifying the response surfaces of the process over a range of conceptual designs. The following diagram shows the experimental arrangement:"

Jan 1, 1998

By Feng Xue, Mi Xujun, Peng Lijun, Yin Xiangqian, Liu Dongmei, Xie Haofeng, Huang Guojie, Yang Zhen

The Age-hardening Cu-Cr alloys are extensively used in integrated circuit lead frame, railway contact wire, resistance welding electrode and continuous casting mold copper plate, owing to having an excellent combination of high electrical or thermal conductivity and high strength. High temperature performance is very important during the service process. Effect of Magnesium and Zirconium on softening behavior of Cr-Cr alloy are investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). During the softening process in the Cu-Cr alloy, the recrystallization process, grain growth and Cr precipitates coarsening are observed. The addition of Mg or Zr to the Cu-Cr alloy, the resistance to elevated temperature can be significantly improved, owing to being restrained the growth of the precipitates by segregating along precipitates surface. INTRODUCTION Age-hardening Cu-Cr system alloys can be widely uesed in many fileds such as electrodes for spot welding (Hatakeyama et al., 2008; Cheng, Shen & Yu, 2013; Zhou et al., 2016; Chbihi, Sauvage & Blavette, 2012), intergrated circuit lead frame (Hatakeyama et al., 2008; Cheng, Shen & Yu, 2013; Zhou et al., 2016; Liu et al., 2006; Pang et al., Xia et al., 2012; Wang et al., 2009; Huang et al., 2003; Cheng, Yu & Shen, 2014; Zhang et al., 2016; Li et al., 2007) and railway contact wire (Cheng, Shen & Yu, 2013; Zhou et al., 2016; Chbihi, Sauvage & Blavette, 2012; Liu et al., 2006; Pang et al., Xia et al., 2012; Wang et al., 2009; Huang et al., 2003), because it has high strength, good electrical and thermal conductivity. The precipitation behavior of binary or ternary Cu-Cr alloys had been investigated by many researchers (Chbihi, Sauvage & Blavette, 2012; Peng et al., 2017; Batra et al., 2002). In addition, to obtain additional mechanical properties without much deterioration in electrical conductivity, trace addition of alloying elements like Zr, Ag, rare metals (Y and Ce) and Mg are added into Cu-Cr alloy. The addition Mg to Cu-Cr alloy accelerated the process of precipitates nucleation and restrained the growth of the precipitates by segregating along precipitates surface during aging, which enhanced the stability of the deformation microstructure and improved the mechanical properties of the alloy (Zhao et al., 2018). Additional zirconium in Cu-Cr alloy enhances the strength by the decrease in inter-precipitate spacing of Cr precipitates and the formation of Cu5Zr phase (Chihiro, Ryoichi & Kazue, 2008). Owing to the decrease in inter-precipitation spacing of Cr precipitates and to the Ag-atom-drag effect on dislocation motion, the addition of Ag can increase in strength, stress relaxation resistance and without much deterioration in electrical conductivity (Chihiro, Ryoichi & Kazue, 2008). The enhance in strength and electrical conductivity of the Cu-Cr-Zr alloy by adding Ce and Y elements are attributed to removing oxygen and sulfur from as-cast alloy (Li et al., 2006). However, the effect of Mg or Zr element on microstructure and properties of Cu-Cr alloy during the softening process are not clear. Therefore, Microstructure evolution and properties of a Cu-Cr systems alloy were investigated in detail by OM and TEM. The Relationship between microstructure and properties of Cu-Cr systems alloy was also discussed.

Jan 1, 2019

By Haibin Ma, Jie Song, Qingyou Han, Xiaoming Wang, Wei Vian

In the grain refinement of aluminum, Al3Ti and TiB2 particles are introduced to reduce the casting grain size down to 200 micrometer level, which makes cold working possible. The particles are brought in by the addition of Al-Ti-B type master alloys. It is generally believed that TiB2 particles are stable and nucleate a-Al grains in solidification in the presence of extra titanium than the stoichiometry of TiB2 from the dissolution of Al3Ti particle in the master alloys. Titanium in solution either form Al3Ti layers on the surface of TiB2 particles or as solute to promote the nucleation and to restrict the growth of a-Al grains. However, a consensus on a grain refinement mechanism is still to be reached due to the lack of direct observation. This paper presents finding on the TiB2/Al3Ti interfaces in an aluminum matrix. It demonstrates a strong epitaxial growth of Al3Ti on the surface of TiB2 particles, a sign of the formation of an Al3Ti layer on the surface of TiB2 particles in grain refinement practice. The Al3Ti layer has a crystal coherency with a-Al and hence offers a substrate for heterogeneous nucleation of a-Al grains.

Jan 1, 2015

By R. D. Brown

"AbstractOver the past five years, tax rates in the Canadian mining industry have skyrocketed upward across Canada, as both federal and provincial governments have sought to increase their share of mining revenues.However, the past few years have not only brought high tax rates to the industry, but also a number of important new federal and provincial tax incentives.In large part, these incentives ~ special credits or reduction in tax for carrying out specific exploration, processing or other activities - have helped to moderate the adverse effects of the higher tax rates and have provided inducements for exploration and processing activities which might not otherwise have been undertaken.However, the effectiveness of certain of these incentives can be questioned: our over-all tax structure now consists in large part of punitively high marginal rates with some extraordinarily generous but capricious tax reductions for specific activities and may not be in the best long-term interest of either the industry or the nation.A rational tax structure, with moderate and stable tax rates, together with reasonable incentives confined to activities specifically requiring them, could be a more effective spur to investment than the present tax and incentive jungleIntroductionIN THE YEARS since federal tax reform, the mining industry in Canada has faced a continued escalation in its tax burdens as federal and provincial governments have leapfrogged each other in imposing new and higher taxes on the industry. The result has been that marginal tax rates imposed on mining and processing activities throughout Canada have jumped to hitherto unparalleled levels."

Jan 1, 1977

By Iina Vaajamo, Jani Jansson, Lauri Pesonen

In pyrometallurgical operations, structural integrity of a high temperature furnace plays a crucial role in the overall safety, profitability and ecological footprint of the plant. Furnace integrity is related to how reliable a furnace is and it can be compromised, for example, by having poor operating and maintenance practices, an inefficient cooling system and flaws in the overall furnace design. These flaws and poor practices might lead to unexpected shutdowns, production losses, increased emissions, or worse. This paper presents the main factors to consider when engineering a furnace and developing its operating practices, while ensuring safe and reliable operations without compromising process efficiency and quality of the final products. In this respect, Outotec’s solutions for the cooling system and for automation systems like PROSCON, Process Advisor, Sentinel and our Smelting Information Management System, are also introduced.

Jan 1, 2015

By R. W. Luhning, S. D. Gittins, J .. A. Haston

"The Underground Test Facility (UTF) project operated by the Alberta Oil Sands Technology and Research Authority (AOSTRA) north of Fort McMurray has achieved marked success in field testing mining access and horizontal well in situ recovery of bitumen from the Athabasca oil sands.Mine access has provided for effective placing and operation of horizontal wells in the oil sands from a tunnel system in the underlying limestone. Performance of the in situ recovery process, Steam Assisted Gravity Drainage, has substantially exceeded forecasts made at the start of the project. Over-all results of the program to date show great promise for horizontal well in situ technology as a competitive source of bitumen from Alberta's vast oil sands deposits. The potential economics of a commercial expansion at the site are reviewed in this paper.IntroductionIn situ recovery o f bitumen from the Athabasca oil sands has puzzled the oil industry for many year s, but a breakthrough appears close at hand. The Underground Test Facility (UTF) project initiated by the Alberta Oil Sands Technology and Research Authority (AOSTRA) has had notable success in the piloting of horizontal well processes, which offer prospects for commercial development even under the highly competitive situation facing the Canadian industry . This paper describes the project briefly and presents the potential economics of commercial development on the UTF lease."

Jan 1, 1990

By R. K. Mishra, A. Kula, X. Jia, M. Niewczas

The mechanical properties of Mg-Gd and Mg-Y solid solutions have been studied under uniaxial tension and compression between 4K and 298K. The results reveal that Mg-Gd alloys exhibit higher strength and ductility under tension and compression attributed to the more effective solid solution strengthening effect and grain boundary strengthening. Profuse twinning has been observed under compression, resulting in a material texture with strong dominance of basal component parallel to compression axis. Under tension, twining is less active and the texture evolution is affected mostly by slip. The alloys exhibit pronounced yield stress asymmetry and significantly different work-hardening behaviour under tension and compression. Increasing of Gd and/or Y concentration leads to the reduction of the tension-compression asymmetry due to the weakening of the recrystallization texture and more balanced twinning and slip activity during plastic deformation. The results suggest that under compression of Mg-Y alloys slip is more active than twinning in comparison to Mg-Gd alloys.

Jan 1, 2015

By P. J. Finnis

This paper describes the use of wire rope on open-pit mining equipment, giving specifications and examples of the performance achieved. Installation methods are also discussed, making the paper of considerable practical use to mine operators.

Jan 1, 1973

By A-A. Bogno, M. Rappaz, J. Valloton, H. Henein

"Rapid solidification of Al-Cu droplets of eutectic composition was carried out using Impulse Atomization in an argon atmosphere, to study the microstructures forming at different cooling rates and undercoolings. Two distinct morphologies were observed within the investigated Al-33wt%Cu droplets microstructures: (i) A regular lamellar morphology and (ii) an undulated morphology. The volume fraction of each type of morphology was measured as a function of the droplet size and the nucleation undercooling was deduced using the hypercooling limit equation. The scale of the microstructures was determined through measurements of inter-lamellar spacing across and along the growth direction. Growth velocity and undercooling were deduced using Jackson and Hunt (1966) eutectic growth theory. Finally, mechanical properties were estimated through micro-hardness analysis using a Vickers hardness tester, revealing exceptional properties for an aluminum-copper alloy. Indeed, the hardness values, increasing with growth rate and undercooling, were 3 times higher than the values obtained in hypo-eutectic Al-Cu alloys.INTRODUCTION Eutectic alloys are very attractive due to their good fluidity allowing ready shaping of parts in casting processes as well as in thermal spray deposition. In addition, they yield microstructures with high mechanical properties, by the virtue of their scale/size which is defined by the solidification parameters and the thermodynamic and thermophysical properties of the given alloy. Therefore, it is important to understand the relationship between the microstructures and the solidification parameters of eutectic alloys in order to control their solidification path and mechanical properties. The latter could be improved by either adding an appropriate strengthening component to a base eutectic material (Böyük, MaraslI, Kaya, ÇadIrlI, & Keslioglu, 2009) or by refining the microstructures for more effective dislocation pinning (Campbell & Campbell, 2003). Tailoring the microstructure can also be beneficial to chemical (Freitas, Osório, Spinelli, & Garcia, 2014; Osório, Freire, Caram, & Garcia, 2012) or electrical (Kaya, 2012) properties of the material. Eutectic-type microstructures, usually formed from liquid (eutectic transformation) or solid (eutectoid transformation), are made up of two or more different phases, generally of lamellar or fibrous (rod like) morphologies (Kurz & Fisher, 1998). In general, a binary eutectic structure can be regular (when both phases are non-faceted) or irregular (one of the two phases is faceted), the two solid phases having roughly the composition of the liquid from which they are formed."

Jan 1, 2017

By M. G. Rylatt, G. M. Popplewell

"Production from Canada's first diamond mine is planned for the last quarter of 1998. The climatic conditions and the variation in kimberlite types to be treated have lead to the development of a compact and flexible processing plant.High kimberlite moisture contents and winter temperatures below -40°C have dictated a process flowsheet with limited in-circuit storage to reduce materials handling difficulties. The latest developments in High Pressure Grinding Roll technology will be used to liberate the valuable diamond, reduce diamond breakage, and increase fines production to reduce the amount of material for down stream processing in the Heavy Medium Separation section.A varying heavy mineral concentrate yield has lead to the development of a final Recovery section that will incorporate Attrition Milling and Wet High Intensity Magnetic Separation for concentrate reduction. The latest developments in diamond X-ray sorting will be used to produce a final diamond concentrate for mechanical sizing, weighing and packing.Fine tailings thickening will utilise Deep Bed Compression type thickeners. This relatively new technology can produce;i) high underflow densities at low flocculant dosage rates, andii) clear overflowswith a smaller thickening area than conventional high-rate thickeners."

Jan 1, 1998

By Liguang Wang

The froth phase in flotation has received much less attention than the pulp phase despite the fact that froth stability plays an important role in determining flotation performance. Froth stability is largely determined by the stability of thin foam films, which in turn has a strong correlation with the critical rupture thickness (Hcr) of the films. In the present work, a new approach to predicting the Hcr values of thin foam films in flotation froth phase was proposed and examined. The Hcr values were calculated using an advanced capillary wave model with input parameters being surface tension, film radius, capillary suction pressure, and intersurface force. The intersurface force was estimated by using the Stefan-Reynolds lubrication approximation to fit the measured thinning rates of single foam films formed in a Scheludko ring cell, where the film radii were less than 50 microns and were kept constant during the film-thinning process. A comparison between the predicted and experimental Hcr values was made for the films with the use of sodium chloride as background electrolyte and in the presence of various frothing reagents such as methyl isobutyl carbinol (MIBC), polypropylene glycol with an average molecular weight of 400 (PPG400), and sodium dodecyl sulphate (SDS), at different concentrations and film radii. It was found that the model correctly predicted the trends of Hcr-versus-concentration and Hcr-versus-film radius curves. Moreover, the predicted Hcr values matched well with the experimental ones of the foam films containing either SDS or PPG400. For the foam films containing MIBC, however, the model overpredicted the Hcr values. The reason for this discrepancy was discussed.

Jan 1, 2016

"The successful commissioning and ramp up of the Albion Process™ at the GPM Gold Project relied on the successful scaling up of the process from batch and continuous pilot plant campaigns (Voigt et al., 2015). Critical information about reaction kinetics and residence time, grind size and pulp density were determined at the laboratory scale and successfully applied to the commercial scale. A limitation of small scale testwork, is that some parameters cannot be measured reliably and scaling up is a function of the physical size of the equipment which isn’t possible to test with laboratory scale equipment. Oxygen mass transfer rate is one such parameter since this is a complex interaction of many factors including slurry temperature, solution and slurry chemistry, slurry viscosity, agitator type, dimensions and power, oxygen bubble residence time, oxygen purity, tank geometry and oxygen injection technique. Oxygen generation represents an important operating cost for the Albion Process™. Pivotal to the Albion Process™ operating economically at atmospheric pressure is the capability to efficiently transfer oxygen while utilising as much oxygen injected to the process as possible. To respond to this Glencore Technology developed the HyperSpargeTM supersonic gas injector. This paper compares the HyperSparge™ against other sparging techniques to quantify the benefits of oxygen injection via a supersonic gas jet on scale up of the oxygen mass transfer system. The paper then examines plant survey data from the GPM Gold Project to demonstrate the very high oxygen utilisation that can be achieved with a correctly designed oxygen mass transfer system.INTRODUCTION One of the main challenges in chemical reactor design is the scale-up of processes from the laboratory to industrial scale. Processes which cannot be faithfully simulated with an experiment at the laboratory scale face challenges due to the physical dimensions and complexity of full scale operation. One example of this is the design of oxygen mass transfer systems in atmospheric oxidative leaching circuits such as the Albion Process™. A number of constraints associated with the use of laboratory scale equipment to design full scale circuits are involved in gas mass transfer processes in agitated slurries such as the Albion Process. Chiefly, typical laboratory and pilot size equipment lacks the required volume to provide useful design data without relying on empirical correlations: the specific agitator power input is artificially high, the bubble residence time in the vessel is artificially low, the oxygen partial pressure at the base of the vessel is artificially low and the oxygen delivery method may differ significantly to the industrial process. Further, the dynamic nature of the process introduces additional impacts on gas mass transfer, including the presence of solids, recycle streams and minor elements, plus the variances within the reality of a process plant such as disruptions or variance of feed quality."

Jan 1, 2017

By Michel Ruel, Ali Soltanzadeh, Benjamin Légaré

High fidelity commercial process simulation packages can be used at different stages of a greenfield project, from initial plant design to operator training in the later stages. However, there are several factors that make the software less attractive for small and medium size brownfield projects, such as the licensing cost and the fact-finding manpower required for model design and simulator maintenance. In this paper a different approach is described. The knowledge gathered from operating personnel was used to implement higher level models based on plant data, operating heuristics, and experience rather than detailed component-level models. The computing platform used was a low-cost, well-established, control system vendor-independent software. Throughout this paper we demonstrate the success of implementing this model-based approach using two industrial examples. The first example is a simulation of the carbon monoxide (CO) distribution system at a metallurgical complex. The purpose of this simulator was to test new control strategies and PLC programs prior to implementation. CO being a toxic combustible gas, validation of the suggested control system changes was necessary for plant safety. Simulation of specific operating conditions helped alleviate concerns and improved plant-wide acceptability of the new operating philosophy. The second example is a boiler simulator at a petrochemical plant. The operator training simulator (OTS) was designed as a platform for experienced operators to practice handling rare or abnormal conditions. A customized medium-fidelity model was developed for this targeted application where the cost of a full scale high-fidelity model could not be justified.

Jan 1, 2016

By V. V. Pankov, W. R. Chen, L. R. Zhao

Diffusion nickel aluminide and overlay NiCrAlY coatings were deposited on single crystal Ni-base superalloy CMSX-4 substrate using the chemical vapour deposition and cathodic arc evaporation techniques, respectively. The NiCrAlY coating underwent a post-deposition heat treatment in an argon atmosphere at 1100°C for 2 hours. All the coated specimens were subjected to furnace cyclic oxidation testing at 1000°C up to 1500 one-hour cycles. The morphology, elemental composition and phase constituents of the oxide scales formed on the coating surface were analyzed using scanning electron microscopy, energy-dispersive spectroscopy and X-ray diffraction. It was observed that the diffusion aluminide coating experienced accelerated weight gain at an early stage of the test (150-400 cycles), whereas the overlay NiCrAlY coating fabricated by cathodic arc evaporation maintained steady-state weight gain throughout the entire 1500 cycle test duration. This difference in oxidation behaviour between the two types of coatings is attributed to the early development of nickel-aluminum spinel on the surface of the diffusion aluminide coating, in contrast to the stable aluminum oxide scale formed on the overlay NiCrAlY coating during cyclic oxidation testing.

Jan 1, 2015

By H. Saeedi Ali, A. J. Monhemius

"Anglo Asian Mining’s Gedabek mine is situated in the Lesser Caucasus mountains in Western Azerbaijan. The ore body is a complex copper-gold porphyry deposit, comprising intermixed oxidized, transition and sulphidic gold and copper-bearing ores. Gold in the sulphide ores is generally not refractory and is recoverable by cyanide leaching, but the secondary copper minerals, which are also cyanide soluble, lead to high cyanide consumptions. Ore processing at Gedabek is by agitation leaching for high grade ore (>1g Au/t) and heap leaching for lower grade ore. In order to cope with the high copper concentrations in the cyanide leach liquors, a unique combination of resin-in-pulp for selective gold extraction and SART processing for copper removal and cyanide recovery is used. In 2015, a flotation plant was added to treat the tailings from the agitation leach plant before the tails are sent to the tailings dam. This plant produces a copper sulphide flotation concentrate and also recovers some of the residual gold and silver in the tailings. Since February 2017, due to lower grades of gold and higher copper in the feed ore, the decision was taken to alter the flow sheet and to carry out flotation ahead of agitation leaching, to reduce the cyanide consumption during leaching by removing soluble copper minerals. The paper compares and contrasts the performance of the plant in the two configurations, namely, (i) leaching followed by flotation and (ii) flotation followed by leaching.INTRODUCTION In May 2009, Anglo Asian Mining started open pit mining for gold on its Gedabek property in the Lesser Caucasus Mountains in western Azerbaijan. Gedabek is situated on the highly mineralized Tethyan Belt that runs from the Himalayas to the Balkans. The ore body at Gedabek is a complex copper-gold porphyry deposit, comprising intermixed oxidized, transition and sulphidic gold-bearing ores. The sulphidic ores contain mainly pyrite and chalcopyrite, with some secondary copper sulphide minerals, such as bornite and chalcocite, and minor amounts of sphalerite, galena and tetrahedrite. Gold in the sulphide ores is generally not refractory and is recoverable by cyanide leaching, but the secondary copper minerals, which are also cyanide soluble, lead to high cyanide consumptions and passivation of free gold."

Jan 1, 2017

By Tom Gaines, G. S. Brant, J. G. Debanne

"AbstractThe Bonnie Glen oil field, one of Canada's largest, lies about fifty miles southwest of Edmonton, Alberta. One hundred and thirty-eight wells have been completed in this field since its discovery in January, 1952. Five different procedures have been used in completing the producing wells.The reservoir is an Upper Devonian biohermal reef with good porosity and uniformly high permeability. The top of the reef is quite flat but the flanks slope at angles approaching 20 degrees from the horizontal. The reservoir has a gas cap with a maximum thickness of 400 feet, an oil column of 300 feet, and a :porcus aquifer of over 300 feet. The reservoir pressure is now 2,400 pounds per square inch gauge at datum ( -4100 M.S.L.).Because of the high permeability and the high •pressure, lost circulation and resultant blowouts are a particular hazard in drilling at Bonnie :Glen field. To reduce the dangers of blowouts, it is general practice to run casing to the top of the reef. If the reef is encountered 'high' it was usual practice to run a liner and perforate for completion. Wells penetrating the •reef below the gas/oil interface were either completed in open hole or through casing perforated opposite the oil pay, with the former method more frequently used. Eight wells were completed by the Humble-Otis permanent-type completion, and recently five high wells were completed open hole with the gas •cap exposed. This latter completion, 'tubing submergence', has proved highly satisfactory thus far.The open-hole type of completion is cheaper than the liner perforation method and results in better well performance. More experimentation and data are needed before the tubing submergence method can be recommended unqualifiedly. but all evidence thus far favours its use in reef reservoirs."

Jan 1, 1955

By Patrick R. Taylor, T. A. R. Putra

A review of various methods to treat high arsenic copper concentrates through pyrometallurgical processing is presented. Examples are drawn from various past and current operations and research. Various aspects of the engineering alternatives for treatment methods are discussed. Some of the methods discussed include: controlled oxidation roasting, adaptation of some smelter technology to accept higher amounts of arsenic, complete oxidation with arsenic fixation; sulfation roasting; acid baking, soda ash roasting, and others methods. Other topics include: a short discussion of other problematic impurities; the effects of arsenic on copper electro-refining and product purity; and methods for the ultimate disposal, or marketing, of the arsenic. The latest work being done at the Colorado School of Mines on soda ash roasting is also presented.

Jan 1, 2014

By M. Sukhram

In the year 1992, T.A. Utigard published a paper titled "The measurement of the heat-transfer coefficient between high temperature liquids and solid surfaces." In that work, he instrumented an agglomerate of materials with thermocouples to infer the heat transfer coefficient of a high temperature liquid on a solid. The purpose of that research was to help in the design and operation of metallurgical reactors. Since that time there have been many researchers that have worked to characterize heat, mass, and momentum transfer phenomena in high temperature metallurgical processing operations. This paper presents results from the author’s experience with instrumenting thermocouples in copper elements coated with carbon to infer velocity of high temperature liquid metals. It also presents a methodology to determine velocity of a high temperature liquid by inferring the local heat transfer coefficient at a solid-liquid interface

Jan 1, 2015

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 S. Beskri, N. Geoffroy

When metallurgical plants are designed, a lot of consideration is almost always given to material selection and possible damage mechanisms. Materials engineers are generally involved and will strive to select optimal alloys or refractories for the design conditions. Once in operation however, things often change. Equipment is overstressed to increase production, corrosive leaks are not always promptly addressed, proper welding procedures are disregarded, etc. This paper describes various cases from the mining and metals industry where serious mishaps, associated consequences, and costs could have been avoided if simple and proactive steps had been taken. It also presents a strategy, based on safety reviews, to help predict and prevent damage to critical pieces of equipment.

Jan 1, 2015