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By P. A. Riveros

This paper describes the leaching of the common copper minerals tennantite (Cu12As4S13), tetrahedrite (Cu12Sb4S13) and enargite (Cu3AsS4) in acidic media using Fe(SO4)1.5, FeC13 or 02 as oxidizing agents. At temperatures <100°C, tennantite dissolves slowly in Fe(SO4)1.5-H2SO4 media, and the rate is directly proportional to the area of the sized tennantite. The rate increases sharply with increasing temperature and the apparent activation energy is 69 kJ/mol. Increasing Fe(SO4)1.5 concentrations slightly increase the tennantite leaching rate. The kinetics of dissolution of disks of synthetic iron-bearing tetrahedrite in Fe(SO4)1.5-H2SO4 media are linear; the leaching rates are slow but increase significantly with increasing temperature, with an apparent activation energy of 120 kJ/mol. The dissolution of sized particles of natural Ag-bearing tetrahedrite in FeC13- HC1 solutions proceeds according to the shrinking core model, and both Cu and Ag dissolve at about the same rate, provided that the total chloride concentration of the solution is sufficiently high to solubilize the AgC1 reaction product. The leaching rates are slow, and the apparent activation energy is 116 kJ/mol. The addition of sulphate ions to the FeC13-HC1 system reduces the tetrahedrite leaching rate to values similar to those realized in the Fe(SO4)1.5-H2SO4 system. At <100°C, enargite dissolves slowly in either Fe(SO4)1.5 or FeC13 media, and the dissolution rate obeys the shrinking core model. The rate increases with increasing temperature and the apparent activation energies are 50-64 kJ/mol. The rate increases slightly with increasing FeC13 concentrations in 0.3 M HC1 media. The leaching of enargite at elevated temperatures and pressures was also investigated. Potentially useful leaching rates are achieved above 170°C, at which temperature sulphate, rather than sulphur, is produced. Lower temperatures (130-160°C) lead to fast initial leaching rates, but the dissolution of the enargite is incomplete because of the coating of the enargite particles by elemental sulphur.

Jan 1, 2007

By Ross Gilders, Leo Cheung, C. David Desjardins

"For the past twenty years significant progress has been made in bacterial leaching. In fact, a recent article in the Northern Miner has cited that nearly all new copper production is based on bioleaching. The bacteria that play the predominant role in bioleaching is an obligate chemolithoautotroph called thiobacillus ferrooxidans. These bacteria thrive in areas rich in sulphide and prefer low acid media. In the simplest sense, they metabolize sulphide converting it to sulphate either as acid or as soluble metal sulphates. This process is well known because these bacteria generate acid mine water. Over the last five( 5) years, we have been carrying out development work on creating optimum bioleach conditions for the extraction of metals from sulphide rich ores and concentrates. Recently, a study was carried out on a byproduct sulphide concentrate produced in a tin flowsheet developed for the Mt. Pleasant Mine of ADEX Mining Corp. The objective was to determine whether a bioleach process might successfully leach this sulphide material which contains copper, zinc, iron and, what is more important, trace metals such as Indium, Gallium, and Bismuth. The current work describes the successful recovery of these metals achieving extractions of more than 80% by applying bioleaching techniques. An overview of this technical program forms the basis of this paper.IntroductionBio-Oxidation of metal sulphides has emerged to be one of the leading edge hydrometallurgical processes for the economic extraction of metals from ore and concentrates. The fundamental process involves the bacterial assisted oxidation of sulphide to sulphate yielding metal sulphates which can be subsequently leached by conventional means. The bacteria that play the predominate role is an obligate chemolithoautotroph named thiobacillus ferrooxidans (TF). These bacteria thrive in areas rich in sulphide and occur naturally worldwide. In fact, TF is responsible for generating acid in water (acid mine water) from exposed sulphide surfaces primarily through the oxidation of pyrite. TF bacteria thrive under the proper conditions of temperature and oxygen supply in the presence of sulphides and populations in excess of a million per millilitre (ml) of solution are achievable. Typically, at room temperature, the bacteria will bio-oxidize in a pH range of 1.0 to 3.0. Today, bio-oxidation has been applied commercially with great success for the extraction of uranium, copper, and gold."

Jan 1, 1996

By Dale Coffin

Definition Of A Crisis Crisis \kri-ses:\ An unstable or crucial time or state of affairs whose outcome will make a decisive difference for better or worse (Webster&apos;s New Collegiate dictionary) An event or set of circumstances that could significantly affect a company?s ability to carry out its business, damage a company?s reputation and/or threatens the health, safety and well-being of employees, the community or the public at large You?re Having A Crisis When... . The emergency poses a significant threat to the public or employees . The emergency situation provokes government scrutiny . The company no longer has full control of the situation . The situation has created significant regional, national or international media interest . The corporation?s reputation may be damaged or there is a threat to the bottom line or share value

May 1, 2004

By R. W. Lawrence

Sulphide is an effective reagent in the precipitation of base metals for both metal winning and environmental control. BioteQ Environmental Technologies Inc. has successfully demonstrated in industrial plants that biogenic sulphide reagent can be generated cost effectively and used to win metals such as copper, zinc and nickel from low-grade leach solutions and wastewater. Commercial plants in which sulphide reagent is used to produce high quality treated effluents for discharge directly to the environment are also in operation. Operations utilizing biogenic sulphide reagent for copper recovery from acid drainage and low grade leach solutions are discussed, including those at Bisbee, Arizona, commissioned in 2004 and at the Dexing mine in China, scheduled for commissioning in 2007. In addition, a new application of BioteQ&apos;s technology for the recovery of copper from gold-cyanide solutions, and the regeneration of cyanide, utilizing biogenic sulphide in place of chemical sulphide reagents in the SART process is described.

Jan 1, 2007

By Roger Reed

It is well known that the performance and carbon emissions associated with the modern gas turbine engine depend critically upon the properties of the nickel-based superalloys, particularly those used in single crystal form. However, the design of all alloys in current use has been essentially empirical, or at best heavily reliant upon regression/neural network analysis of experimental datasets. In this paper, alloy design approaches [1] are described which are able to identify new alloy composition spaces which are worthy of experimental study. It is shown that a large amount of design data can be generated, which can be interpreted in different ways. Of course, the success of the approach depends heavily upon the accuracy of the underlying sub-models. Estimates of the creep resistance, cost, castability, density and oxidation resistance are made. It is demonstrated that these methods allow quantitative trade-offs to be made between the properties of interest.

Jan 1, 2010

By G. Portillo

Electrospark Deposition (ESD) is a pulsed-arc micro-welding process characterized by using high current electrical pulses, of a short duration, to deposit an electrode material on a metallic substrate. The short duration of the electrical pulse allows for a low heat input over the substrate and an extremely rapid solidification of the deposited material. As a result, the ESD is capable of a wide variety of microstructures like micro-segregationfree solid solutions, nanostructured grains, metastable structures, and amorphous phases. The present work shows a microstructural analysis of rapidly solidified Al-Ni alloys coatings by the ESD process. Field Emission Scanning Electron Microscopy (FE-SEM) and X-Ray Diffraction (XRD) were performed to present the microstructural evolution as a function of the welding parameters. The phases and non-equilibrium metastable structures present in the alloys, and their distribution, were found to be a sensitive function of the alloy composition; hence its formation is governed primarily by thermodynamic considerations.

Jan 1, 2011

By M. Xiao Bo

In recent years, there has been a heightened interest in the hydrometallurgical processing of sulfide ores and concentrates (especially copper sulfide ores and concentrates) mostly in the USA and Chile. Currently, hydrometallurgical operations account for about 30% of the primary copper production. In the present research, the leaching phenomena of IOCG (iron-oxide hosted copper-gold) ores and concentrates were studied. The IOCG ore, which is characterized as having a predominant amount of magnetite with fine chalcopyrite, is currently the center of attention for new copper resources. Heap leaching of IOCG ore is desirable because of its low cost. However, the leaching characteristics of the ores and concentrates and the mechanisms of copper leaching require investigation. This study defines the factors, which affect the leaching operation, such as the ORP, pH and oxidizing agents. Based on these results, the optimal leaching conditions are provided for pilot column leaching test and ultimately, commercial operations.

Jan 1, 2007

By C. Sartain

In recent years market pressures have been building on companies to develop the next era of mining projects to follow the previous boom in copper projects of the mid 90&apos;s. However the response from the industry has been slow in coming, and somewhat muted. It is clear that there simply have not been the obvious quality projects waiting to be rapidly developed. Many of the known undeveloped copper projects have particular characteristics that have previously prevented their development, including mineralogical complexity in the ore bodies, environmental challenges or particularly difficult geographic locations. This paper describes how the Copper Division of an international mining company, Xstrata plc, is preparing to progressively develop an impressive pipeline of projects, armed with an array of proprietary technologies and with a strong approach towards sustainable development and community engagement. The approach being taken is enabling Xstrata to complement its acquisitive corporate philosophy with a management emphasis on project development and operational optimization and enhancement.

Jan 1, 2007

By Pierre Bénard

To achieve penetration on the energy market, hydrogen must overcome obstacles in the areas of storage, safety and infrastructure. One of the most important is the onboard storage of hydrogen for transportation applications, where large performance gaps exist between the current state of the technology and user expectations. In order to develop and demonstrate viable hydrogen storage technologies for cars, a set of gravimetric and volumetric system targets have been proposed by the US Department of Energy, based on achieving a driving range of 500 km for a hydrogen powered vehicle. A factor of 2 to 3 improvement in both hydrogen storage capacity and energy density is needed along with several other performance goals. Another key issue is safety. Although some of the safety issues can be arguably assigned to misperceptions, hydrogen has specific properties that have to be addressed, particularly in confined geometries where the risk of hydrogen detonations becomes an issue.

May 1, 2007

By M. L. Free

Laboratory scale extraction of metals from heterogeneous materials such as copper ores is often performed using fine material to increase kinetics and reduce sample size requirements and costs. In contrast, commercial extraction is usually accomplished using much larger material sizes than are used in laboratory settings. The large size difference between laboratory testing and commercial application materials makes it difficult to use laboratory test data to accurately predict performance for commercial material. One solution adopted widely in industry is the use of large test columns. Large test columns cost considerably more to set up and run and take much longer periods of time to evaluate than laboratory scale tests with small particles. Consequently, from a cost and data collection efficiency perspective, the development of accurate scale up methods offers significant potential for saving both time and money. This paper provides details for a new approach to correct for scale-up phenomena in heterogeneous material processing.

Jan 1, 2007

By B. T. Lu, J. L. Luo, J. F. Lu

The present paper investigates the chemo-mechanical effect in slurry-erosion corrosion process of carbon steel to understand the synergistic mechanism due to interaction of chemical and mechanical factors. The erosion-corrosion tests were conducted with A1045 steel in slurries comprising tap water and silica sand. Various heat treatments were adopted to achieve different hardness in the test material. The chemo-mechanical effect is evaluated in line with the correlation between the degradation of hardness in the surface layer and anodic current density. During the erosion-corrosion tests, various anodic currents were applied to find the relation between the anodic dissolution rate and erosion rate. The experimental results indicate that the hardness decreased with increasing anodic dissolution. Based on the fact that pure mechanical erosion rate increased with decreasing hardness, this result suggests that the corrosion-induced degradation of mechanical property is a mechanism of corrosion-enhanced erosion. This theoretical prediction is verified by erosion-corrosion experimental results.

Jan 1, 2004

By W. D. Gould, A. Kapoor

Acid mine drainage (AMD) is characterized by low pH and high concentrations of sulfate and dissolved metals such as iron, manganese, aluminum, zinc, and copper. Chemical treatment of AMD achieves pH neutralization and toxic metal removal but also produces large quantities of bulky sludge that requires long-term storage facilities and monitoring. Chemical treatment of AMD achieves only partial removal of sulfate (SO4) and total dissolved solids. Sulfate reducing bacteria (SRB) have been used for the removal of sulfate from industrial process wastewaters. The biological sulfate reduction process generates sulfide and alkalinity. The sulfide produced in the biological sulfate reduction process is used to precipitate metals present in AMD as their respective sulfides and the alkalinity generated is used to neutralize the AMD. This review article will present an overview of biological sulfate reduction processes using SRB, bioreactor configurations, AMD treatment studies, and full-scale systems in operation for the treatment of acid mine drainage.

Jan 1, 2004

By J. Beddoes

The various microstructural factors that influence the creep resistance of y-titanium aluminides are presented and discussed. Titanium aluminides have potential for a variety of intermediate temperature applications in both gas turbine and reciprocating engines. While it is well established that the &apos;fully lamellar&apos; titanium aluminide microstructure offers superior creep properties, the particular influence of lamellar morphology, third phase precipitation, and grain boundary structure in controlling both the primary and tertiary creep behaviour is presented. The results are primarily based on tensile creep experiments undertaken using several titanium aluminide intermetallic compositions processed via powder metallurgical techniques, investment casting and Bridgman directional solidification. The results indicate that lamellar structure and precipitate formation have a major impact on primary creep, while microstructural degradation through both lamellar and precipitate coarsening influence on the onset of tertiary creep leading to fracture. The results are used to design a creep resistant microstructure produced by directional solidification and the effectiveness of this designed microstructure is demonstrated through 10,000 hour creep tests.

Jan 1, 2004

By A. Siegmund, F. Mucciardi, Z. Yuan, B. Bulnes

With conventional heat pipe science as the starting point, a new heat transfer technology --- termed Thermopump technology, has been developed at McGill University and is now being tested at a number of industrial operations. This technology is of particular importance for transferring energy in high temperature / high heat flux environments where solutions based on current techniques are not available. One important application for this technology is in the metals recycling area wherein this technology has been used to make a waterless, non-consumable, high efficiency Thermopump oxygen lance. The viability and efficiency of this oxygen lance have been demonstrated by preliminary plant trials in a reverb furnace for the recycling of lead-acid batteries at the RSR Corporation. Full-scale commercial trials of the Thermopump (TP) oxygen lance have been carried out at the RSR Corporation. The results from these tests will be presented. In addition, some applications of the Thermopump technology for other metal recycling processes will also be discussed in this paper.

Jan 1, 2004

By C. J. Cattarello

"The Langmuir Mine is located seventeen miles south-east of South Porcupine in Langmuir Township.The property was developed as a Joint Venture between Noranda Mines Limited and the International Nickel Company of Canada with Noranda responsible for the operation of the property.The Mine came into production in June 1973 at a rate of 700 tons per day of nickel ore.MINING The mining method selected for the Langmuir Project was a sub-level retreat method. This consisted of driving sub-levels longitudinally in the ore body at 35 foot, intervals with the sub-levels being connected by a ramp from each main level for the use of trackless mining equipment.GENERAL GEOLOGY OF THE LANGMUIR MINE The deposit is situated about 1,000 feet west of the shore of Carmen Bay at the south of Nighthawk Lake in Langmuir Township. The area is underlain by andesite and rhyolite flows with iron formations which are intruded by gabbro, diorite, peridotite and late precambrian diabase dikes."

Jan 1, 1975

By Fathi Habashi

This Historical Metallurgy Note is the second part of a three-part series, the first of which appeared in the November- December issue of the Bulletin. Part III will be published in February, 1998. This series of articles is dedicated to the memory of Nikolai Maximovitch Pereskuryakov (1940-1994), Rector of Saint Petersburg Mining Institute from 1992 to 1994 who passed away unexpectedly at the age of 54, shortly after celebrating the 275th Anniversary of his Institute.

Jan 1, 1998

By J. Shen

Direct methanol fuel cells have been the subject of considerable research in the last decade. Performance levels realized in cells, stacks, and systems show that this technology is a promising power source for a wide range of portable applications. A direct methanol fuel cell (DMFC) operates directly on a methanol fuel stream typically supplied as a methanol/water vapour or as an aqueous methanol solution in liquid feed DMFCs. The fuel streams in DMFCs are usually recirculated in order to remove carbon dioxide and to re-use the diluent and any unreacted fuel in the depleted fuel stream exiting the DMFC. The concentration of methanol in the fuel circulation loop is an important operating parameter because it determines the electrical performance and efficiency of the direct methanol fuel cell system. The methanol concentration in the circulating fuel stream is usually measured continuously with a suitable sensor, and fresh methanol is admitted in accordance with the signal from the sensor. There are many factors to consider in developing a methanol sensor suitable for DMFCs. These factors include sensitivity, cost, size, simplicity, reliability, longevity, concentration range, and dynamic response. In particular, reliability and low cost should be addressed. Methanol concentration sensors measure methanol concentration by means of detecting the variations of physical/chemical properties of the solution. In this work, methanol concentration sensors based on electrochemistry, electric-capacitance measurement, infrared sensing, ultrasound sensing, and other techniques are reviewed to discuss their advantages and disadvantages.

Jan 1, 2005

By P. Turcotte, E. Karampinos

"Construction of underground excavations in squeezing ground conditions faces several technical challenges that can result in delays in production and high costs due to rehabilitation. A review of the behaviour of drifts under squeezing ground conditions was undertaken at the LaRonde mine. In particular it focused on implemented strategies to control the observed large deformations. The mine experiences a large range of squeezing ground conditions, mostly driven by the presence of foliation and high stresses. This results in large deformations over one meter in radius. A comprehensive ground control strategy has been implemented with the aim to manage, rather than arresting drift closure. The evolution and effectiveness of the employed support strategy are discussed based on documented field observations. In complement to the field implementation numerical models are used to provide further insight on the observed squeezing conditions.INTRODUCTIONThe development of underground excavations under squeezing ground conditions is usually associated with excessive rehabilitation and significant failure of ground support due to large deformations. Cost research case studies have concentrated on squeezing ground conditions in tunnelling. An overview of the methods used for the identification and quantification of squeezing and the numerical methods for the simulation of these conditions in tunnelling has been provided by Barla (2002). Numerous support systems that can manage ground deformation are available for civil engineering tunnelling. Nevertheless, the use of these systems in mining would result in high support cost and production delays. Mining operations have higher development rates and shorter service life. This study focuses on the behaviour of underground excavations under squeezing ground conditions in hard rock mining.In a mining context, the magnitude of deformation is usually higher than in civil engineering tunnelling as there is a higher tolerance for operation purposes. Potvin and Hadjigeorgiou (2008) noted that in mining, squeezing is encountered when the total displacement of an excavation reaches at least tens of centimeters over the life expectancy of a supported drive and is associated with considerable damage to the ground support."

Jan 1, 2015

By J. A. Haskin

The Engineering Department at Flin Flon has the following responsibilities: 1. Underground Surveying. 2. Open-Pit Surveying and Supervision of Blasting. 3. Mine Geology and Examination of Prospects. 4. Design of Plant Additions and Improvements. 5. Miscellaneous Field W ork, Reports, etc. The entire surface plant, as well as the underground workings, are located by co-ordinates based on a triangulation system covering an area approximately one mile long by one-half mile wide. The origin of this system and one end of the base-line is the southwest corner of Township 67, Range 29, west of the Principal Meridian. The bearing of the base-line was determined from the township boundary, which runs true north, so that all other bearings are almost astronomical. This is a great convenience when our surveys must be tied to mineral claims, rights-of-way, and land subdivisions. As the base-line extends across Flin Flon lake, its measurement across smooth ice was simple and accurate. The length, slightly over 1,600 feet, has been adjusted for the temperature and tension of the standard tapes used and checked sufficiently to ensure a maximum error of 1 : 15,000. Each angle was repeated ten times, but as no special refinements were used, errors of as much as four or five seconds are possible. The elevation of the origin of the triangulation system was approximately 1,050 feet above sea level. The use of this true elevation in our surveys would have resulted in negative elevations underground as soon as the mine reached a depth greater than 1,050 feet. To avoid this complication we therefore added 4,000 feet to this elevation. The collar of the Main shaft, for example, which is actually 1,072 feet above sea level, appears in our records as at elevation 5,072. Underground surveying, which follows standard practice, is done by two mine surveyors who share three helpers. The meridian is taken underground from two wires hung in either of the two vertical shafts.

Jan 1, 1935

By P. M. Dranchuk

"SINCE their inception, the mineral industries have, from time to time, been confronted by various and sundry problems. These have been identified, attacked and solved by means of a slow methodical process peculiar to these industries. During the past decade, these industries have experienced increasing difficulty in attracting and retaining an adequate supply of manpower. This poses a situation which seems to be unlike those that came before it in that it appears to be immune to those methods of attack which were successful in the past. Despite various attacks upon the problem, its seriousness appears to be increasing at an increasing rate. The point has now been reached where the President of AIME recently expressed the opinion that this is the most serious problem facing these industries at this time (1). Another observer has gone so far as to state, ""Given the motivation and the determination, the crisis in mineral education in Canada, can, in time be met. But it will take a generation if we Start DOW (2)"".Part of the difficulty arises out of the identification and assessment of the problem itself. For, although the manpower shortage has been developing over a fairly long period of time, there still appears to be no unanimity concerning its seriousness and the nature of the threat which it poses. Some observers continue to maintain that the current situation is not new at all, but is merely the reappearance of something old which is cyclic in nature. They observe that in the past there were numerous periods where the mineral industries encountered manpower shortages but that, in each instance, the situation eventually rectified itself. Furthermore, they draw attention to the fact that the current problem is not confined to the mineral industries but that in fact all industries are experiencing an increasing manpower shortage. They are therefore confident that if left alone the present problem will eventually disappear."

Jan 1, 1967