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By N. Morrison, I. Holl, R. Welyhorsky, A. Hempstock

ABSTRACT: The Victor diamond mine is located in the James Bay lowlands, 90 km west of the First Nations village of Attawapiskat. The project was the first of its kind in northern Ontario. The process plant was designed to produce a 95 to 98% by weight diamond concentrate through three stages of comminution, dense medium separation, and proprietary X-ray technology for final recovery. The plant was commissioned over a period of six months, commencing prior to substantial completion of construction. Through effective planning of the commissioning phase, the Victor mine start-up was safely completed nine months ahead of schedule.

Jan 1, 2011

By L. Hacini

The start-up is the most critical phase of the cell life, as an uncontrolled start-up could lead to early infiltrations, instabilities, and in some cases to the cell death. Lots of efforts are put to increase the lifespan of cells, as it has a major impact on both the operating costs and the environmental footprint of the aluminum industry. Obviously, a true size test on a cell is a resources- and time-consuming approach that could be used only to validate mature concepts. Moreover, numerical modelling is a low-cost and versatile tool capable to test a wide range of potential ideas and concepts. In the present article, a thermal electrical mechanical slice model is presented. This model describes the preheating and bath periods of a P155 aluminum cell start-up, as used at the Grande Baie smelter. The impact of sodium diffusion and expansion is also included in the model. This model will be useful to study different problematical issues such as the global behaviour of lining materials, shell and cradle deformations during start-up and several start-up scenarios. Such a model will also be able to answer some interrogations regarding early infiltrations and their impact on the lifespan of the electrolysis cell.

Jan 1, 2011

By E. Latorre, T. S. Golosinski

ABSTRACT; his paper proposes new methodology to define the pit limits that yield the maximum net present value (NPV) for a deposit, under a given economic scenario and for a given discount rate. The method uses an algorithm that combines dynamic programming and heuristics. It was tested for evaluating deposits with different sizes and various grade distributions. For the discount rate of zero, the results confirm that the economic pit limits are the same as that defined using Lerchs Grossman method. However, when discount rates higher than zero are used, the pit limits differ, yielding a higher NPV.

Jan 1, 2011

By Masatsugu Morimitsu

This paper introduces new technology of oxygen evolution anodes which can be applied to produce copper, zinc, cobalt, and other metals by electrowinning. The anode consists of nano iridium oxide particles dispersed in amorphous tantalum oxide matrix as a catalytic layer formed on a titanium substrate. The anode can reduce oxygen evolution potential by 0.25 to 0.55 V compared to commercially available lead alloy anodes and can suppress unwanted side reactions such as manganese oxyhydroxide, lead oxide, cobalt oxyhydroxide which occur during oxygen evolution in the electrowinning solutions. This technology is effective for environmentally friendly electrowinning processes with low energy consumption and less anodic deposition.

Jan 1, 2011

The SART (sulfidisation, acidification, recycle, and thickening) process is an effective way to separate copper and cyanide from each other in the waste stream of gold processing plants using cyanidation. Factorial experimentation has been conducted to create models of copper recovery, cyanide recovery, acid addition, and oxidation I reduction potential during SART. Economic analysis of the resultant models showed that SART is best operated with a sulfide to copper molar ratio of around 0.56, a pH of 4, and a minimised cyanide to copper molar ratio. The experiments also showed that thickening time may have drastic impacts on SART performance.

Jan 1, 2011

By Ham. Y. M.

The corrosion behaviour of Al-B4C metal matrix composites immersed in 2500 ppm boron-containing H3B03, 0.5 M K2SO4, and 3.5% NaC1 solutions was investigated. Effects of B4C particle volume fraction on the corrosion behaviour of composites were studied using potentiodynamic polarization and electrochemical impedance spectroscopy techniques. Scanning electron microscopy was employed to study the surface morphology of the material before and after corrosion. Results show that all materials investigated are more corrosion resistant in 2500 ppm boron-containing H3B03 than in other solutions. No appreciable corrosion was observed in boric acid and sulfate solutions in contrast to an obvious pitting in NaC1 solution for both base alloy and composites. The preferential pitting sites are the interfaces of Al/Fe intermetallics for the base alloy, and the A1/B4C interfaces for the composites. Increasing the volume fraction of B4C particles in the composite decreases its corrosion resistance of Al-B4C composites.

Jan 1, 2011

By Jérôme Girard, Shiu Kam, Sue Longo

"Historically, tailings management in a northern climate has involved the deposition of tailings into the Tailings Management Area (TMA) as conventional slurry. This type of system is obviously viable but presents challenges that are difficult to manage as circumstances change over the life of mine. These issues can include:? Increases in mill throughput, and? Life of the TMA for the life of mine.This case study will present how thickened, high-density, non-segregating tailings are used as an alternative to conventional slurry disposal to achieve greater storage capacity and enhanced environmental performance for a gold tailings facility in a northern climate. This paper will focus on how this change in deposition strategy accommodated the increased throughput of the mill and the increased life of mine. Specifically, the paper will discuss the addition and integration of new processes to the exiting mill system to accommodate the tailings management issues. It will highlight the challenges from laboratory testing to pre-feasibility to the engineered design of the thickened tailings system implemented at Musselwhite Mine.BACKGROUNDGoldcorp Canada’s Musselwhite Mine, in Northwestern Ontario (120 km north of Pickle Lake), is an underground gold mining operation that began production in 1997. The current mill throughput is about 4000 tpd (1.4 Mtpa). Gold extraction is based on a CIP process with cyanide destruction.The existing tailings management area (TMA) is located about 2 km southwest of the mill complex. The TMA is contained by high ground to the north and to the west and flanged by a moraine ridge along the south side. A number of dams have been constructed along this ridge. The dams were first built in 1996 and subsequently raised in 2000 and again in 2005. Excess tailings pond water is discharged to a polishing pond then released to the environment via a wetland.The TMA was originally designed to contain 13.7 Mt of tailings under a ponded surface for closure. The water cover was to inhibit adverse long-term environmental effects because the tailings contain pyrrhotite and other sulphide-bearing minerals that are potentially acid generating. The design was modified during Stage 3 Construction in 2005 to expand the storage capacity to 17.3 Mt (Golder, 2005). As of end of 2009, over 16 Mt of tailings had been deposited in the TMA. The slurried tailings were historically deposited at 50% solids."

Jan 1, 2011

By R. P. van Hille, N. Mooruth

Remediation of acid rock drainage (ARD) was performed within a linear flow channel reactor (LFCR) via a floating sulphur biofilm (FSB). A full sulphur species material balance was conducted in order to characterize the sulphide oxidation. The reactor was able to achieve an 82% and 93% conversion of sulphide with a hydraulic residence time of 2 and 5 days respectively. 92% and 55.5% of the converted sulphide reported to the biofilm as sulphur for the 2 and 5 day residence times respectively. The mass transport limitations within the biofilm were identified via a dissolved oxygen gradient profiling system.

Jan 1, 2011

By A. Eltringham

Operations downstream of mining and beneficiation are still being subjected to increasing scrutiny as highly capitalized projects have been either slow to achieve their targets or have actually failed to do so. Leaching and smelting projects have fundamentally high calls on capital and technology as reaction rates are increased and the capture and disposal of unwanted products are subjected to greater restrictions. Separating value from waste inherently becomes riskier as the purification of the desired product imposes greater demands on the process to produce benign wastes. When we superimpose on the chemistry of the project severe predictions of throughput rates, that bring in facets of manufacturing, we are introducing complexities that the records show are not handled well. This paper discusses some of the more common challenges that operators face and what methods are available and are likely to be successful in preventing the loss of value as projects are brought on-stream. This thinking needs to start much earlier and at greater intensity than our industry has normally chosen to employ.

Jan 1, 2011

By C. M. Díaz, P. J. Mackey, P. Coursol

In a recent paper [1], the present authors discussed calculated energy consumption numbers in copper sulphide concentrate smelting for four different smelting technologies. For the present study, from among these technologies, they selected the Noranda/Teniente continuous bath smelting followed by Peirce Smith (PS) converting route to investigate the impact on total energy requirement of some key process variations, such as tuyere injection of dry concentrate vs. slingering of wet concentrate over the molten bath, continuous converting vs. conventional batch PS converting and commercially proven slag cleaning alternatives. In their calculations, the authors used the same thermochemical model and methodology used in their earlier paper. This approach to explore plant design options provides an interesting basis for evaluating flowsheet modifications that could lead to significant copper smelting energy savings. The METSIM software was used in the present paper to carry out heat and mass balance computations for 8 different flowsheet configurations. The results are presented and discussed in the paper with respect to copper recoveries, energy requirements and CO2 emissions.

Jan 1, 2011

By S. Makni, S. Koppalkar, A. Bouajila

This paper reviews briefly the gravity recovery involving conventional gravity separators and centrifugal gravity separators. The advantages of semi-continuous gravity separators will be discussed. Techniques for upgrading the gravity concentrates will be addressed briefly. The research efforts in optimizing semi-continuous gravity separators will be recalled. Innovative gravity circuit for eliminating or minimizing the use of complex processing schemes will be reviewed. On-going gold gravity research at COREM has revealed that gold particle shape transformation is the main factor explaining the lower recoveries of the plant units. Efforts to devise possible remedies for improving gravity recovery at plant will be discussed.

Jan 1, 2011

By P. Moreno

ABSTRACT: The Maras salt terraces, located between Cuzco and Urubamba in the Andes (southern Peru), are living examples of traditional Incan salt production, where present-day artisanal miners produce salt from shallow pans by solar evaporation. In these terraces, natural spring water, eight to nine times saltier than seawater, is used to produce the salt. The field observations and chemical analyses show that the poorly crystalline traditional salt is finer in particle size and contains impurities such as dolomite and gypsum. These differences are the result of shallow pond depth, contamination from wall erosion, and the nonsequential mode of salt crystallization.

Jan 1, 2011

By Dale Dean, Bill Hancock, Raul Mondragon, Carlos Aguilar, Chris Martin

"In 1942, commercial mining operations began in what is now the Lucky Friday Ag/Pb/Zn mine in Idaho’s Silver Valley. Wholly owned since 1962 by Hecla Mining Company, the mine has produced more than 145 million ounces of silver and has been a mainstay producer in Idaho’s Silver Valley for over 70 years.However, by the early 21st century, the mill had fallen, technologically, seriously behind the rest of the industry. Accordingly, starting in 2005, the current mill management team set to revitalizing the milling operation. This paper will describe how the mill was systematically evaluated and the aging infrastructure replaced with more current technology. Driven by internal mill review studies supported by QEMSCAN mineralogical balancing, the mill has in recent years been through waves of upgrading – from the installation of new mechanical and column flotation equipment to the introduction of on-stream analysis, a technology well-accepted around most of the industry but alien to this technologically conservative mining district.The experience at Lucky Friday is a testament to the need for ongoing structured mill optimisation and technology upgrading in established mining operations. This paper will describe engineering experiences associated with upgrading equipment in an operating mill, contained in a confined building. Experiences in teaching the team new ways of operating a mill, and finally the metallurgical rewards that have been reaped will be described.INTRODUCTIONMining in Idaho’s Silver ValleyIdaho’s Silver Valley is a 64-km long valley flanked by the US Northern Rocky mountains, seldom more the 3-km wide, and stretching across much of Idaho’s northern panhandle, roughly 150 km south of the Canadian border. Mining has been continuously active in the area for more than 140 years, during which time, the Silver Valley has become one of the richest silver producing districts in the world, and as of 1985 had out-produced the 500 years of production from the famed Potosi district in Bolivia. Since 1885, almost 100 deposits have been discovered and worked in the district (Chapman, 2000)."

Jan 1, 2011

By V. Aprahamian, T. Cheng, M. Tangen, R. Beauprie

The Royal Canadian Mint has implemented significant process additions since 2005. Installation of a whole new highly automated silver refining circuit has allowed recovery of physical silver from gold and silver dorés . To complement this change, a small Top Blown Rotary Converter has been in operation. On the gold refining side, a new hydrometallurgical process to recover precious metals from Miller Chlorination slag has been developed. Finally, new systems have been put in place to improve treatment of waste water, wet and dry fume and dust.

Jan 1, 2011

By K. Mirkhani, P. Gebski, W. Ying

The campaign life of an industrial metallurgical vessels strongly relies on the quality and quantity of the refractory lining. An operating furnace or converter refractory lining can be assessed either by thermal modeling or by acousto ultrasonic-echo (AU-E) technique or a combination. AU-E is a Non-Destructive Testing (NDT) stress wave propagation technique that has been utilized on a wide variety of smelting vessels for over 12 years with good success. AU-E can determine the thickness of remaining refractory lining, estimate the thickness of build-up or accretion, detect and locate metal penetration and impregnation into the lining, and identify hydrated or cracked areas of refractory. This paper details the AU-E principles, equipment and recent improvements to the data analysis to further improve speed and accuracy. In addition, the paper discusses the AU-E accuracy and limitations through a diverse and vast array of practical examples including a comparison with thermal modeling and physical measurements.

Jan 1, 2011

By Frédéric Flament, Luc Lachance

"The important task of metallurgical accounting that used to be done manually is being more and more automated. Currently available solutions can generate accounting reports without human intervention or almost. However, the practical conditions for fully delivering the promised benefits of those solutions are sometimes overlooked either by end-users or by integrators. The mere fact of filling reports with values satisfying several constraints such as mass conservation constraints does not, by itself, ensure a high quality metallurgical balance. Since managers make decisions based on these reports, it is logical that the metallurgical balance performance be monitored and retrofits be made if necessary. Such retrofits may involve modifications to the measurement strategy or the reduction of the spatial resolution of the material balance model. This requires an estimability and redundancy analysis (ERA) tool to assess the feasibility of the modified model. Since determining by hand the estimability and redundancy of a set of non measured and measured variables is not trivial, even for a medium-sized mineral processing plant, a dedicated ERA tool brings valuable assistance to the metallurgist in charge. The present paper aims first at explaining how a state of the art metallurgical balance is a key enabler for the adoption of a smart process plants paradigm (SPPP) in mineral processing. Then, the fundamentals behind the building of an ERA algorithm are introduced and illustrated by two examples. Finally, the role of an ERA tool in achieving state of the art metallurgical accounting and how it contributes to delivering additional value are discussed.INTRODUCTIONThe Smart Process Plants Paradigm (SPPP)Mineral processors have seen an increase lately in external pressures toward operating performance improvements. Indeed, the globalization of the mining business is a key driver to becoming more productive, more responsive to market changes, to improving corporate governance and reporting standards. Furthermore, mineral processors are also expected by their neighbouring communities to continuously improve their sustainability score. These current pressures differ somewhat from the past ones in leading to a larger than ever number of conflicting constraints that plant managers must concurrently satisfy while maximizing plant profitability. It is in turn not surprising that this context requires actions involving more real-time collaborative actions between more people in more places than ever before."

Jan 1, 2011

By R. Gordon, J. Palich, W. Qian

The EarthProbe DCIP system deploys tightly spaced electrodes connected to a centralized data acquisition system that enables arbitrary selection of current and potential electrodes through relays. Rapid data collection (approximately 1000 readings per hour) and advanced signal processing allow for efficient use of conventional and novel arrays and the removal of natural and cultural noise. What is unique about the system is its electrode and borehole cable design, which allows seamless integration of borehole and surface measurements. EarthProbe operates in four configurations - surface, borehole, borehole-to-borehole, and surface-to-borehole (a variant of the borehole-to-borehole configuration).

Jan 1, 2011

By G. Kolosay, J. Rajala, G. Deschênes, A. Romanov

ABSTRACT: The Kupol project, located in Far East Russia, treats a high-grade, free-milling ore containing 25.5 g/t Au, 298.3 g/t Ag, and 0.5% pyrite,with a P70of 53 microns. Most of the gold occurs as elec-trum and the silver is predominantly present in the forms of acanthite, stephanite, pyrargyrite, andproustite. The mill reached the design throughput of 3,000 tpd six months after start-up. AKnelson con-centratorrecovers10.4% gold and 0.5% silver. Leaching (14.5 hours pre-treatment and 116 hours cyanidation)of gravity tailings is performed with the CANMET Enhanced Leach Process (CELP),using only 490 ppm NaCN (cyanide consumption of 1.1 kg/t). The precious metals are recovered by counter-current decantation and the Merrill-Crowe process. Calcium hypochlorite destroyscyanide and thiocyanate. Overall, gold and silver recoveries for 2008 were 95.4% and 85.6%,respectively (2.8% and7.5% higher than targets). In the first eight months of 2009, gold and silver recoveries were 95.0% and82.6%, respectively. By August 2009, the mill processed 1.42 million tons of ore with production of 1.1 million ounces of gold and 11.3 million ounces of silver. CELP performance was not affected by changes in feed grade and ore mineralogy. Additional modifications to the leaching strategy allowed further reduction in cyanide consumption and effluent treatment costs.

Jan 1, 2011

By Osvaldo A. Bascur, Curt Heftier

The lack of integrated information including the Energy/Utility Suppliers with sufficient detail for analysis causes inefficient operation in metallurgical complexes including the Energy/Utility Suppliers . Defining the right context for information use is essential for sustainable operations. This being said, what are we doing to enable people to act upon information and to be aligned to optimize the use of resources like raw materials, energy, water and consumables for an entire metallurgical complex? Collaboration between all company entities is a key component of improving efficiency. Evolution of web technology and object modeling of enterprise assets enables collaboration across the whole business. Operational troubleshooting occurs more quickly as the organization acts on issues to reduce wasteful operation. This paper presents a real time software infrastructure with tools that give users the ability to sift through available data, transform data into information for business continuous improvement and optimization. We will introduce a new technology for analyzing real time data, information and events using multidimensional analysis of information to detect anomalies based on the statistics of the data classified by time events to reduce the information into action. A new paradigm for collaboration at a local and strategic level is proposed to enable the enterprise to become proactive in dealing with wasted time and products. Three examples from the industry will presented and their benefits highlighted.

Jan 1, 2011

By Tatsuya Oki

Tantalum capacitors can be found mounted on printed circuit boards of domestic appliances such as personal computers. These capacitors contain a considerable quantity of expensive metal tantalum and can be detached and liberated from printed circuit boards by impact breakers. In this study, the size and density distribution of the liberated electronic devices were investigated. Then, tantalum capacitors were recovered from other electronic devices using size separation and pneumatic gravity concentration methods. More than 70% of Newton's separation efficiency was obtained for tantalum capacitors. High Newton's separation efficiency could be also obtained for other types of electronic devices such as chip resistors.

Jan 1, 2011