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"This paper discusses the use of risk assessment and risk management techniques within the Australian underground coal mining industry, within the context of geotechnical risk. The industry works within a pro-active, “enabling” legislative framework, where companies and management apply a range of risk assessment tools as part of their everyday management processes. Different geotechnical risk factors and approaches are reviewed, together with application examples – ranging from mine planning and design, operations, and accident investigations.A particularly powerful resource in each of the above stages of geotechnical management is the RISKGATE system. RISKGATE is an assembled “body of knowledge” structured under different topics across the Australian coal industry, of which three topic areas address rock mechanics issues for both the underground and surface mining sector. This paper will provide an overview of RISKGATE in the context of risk-based rock mechanics applications in underground coal mining."

Jan 1, 2015

By Franco Chiesa, David Levasseur, Bernard Duchesne

A 500kg aluminium AlSi7Mg03 casting has been poured and the metallurgical quality at different locations inside the casting has been thoroughly investigated. It included measuring the local tensile properties (YS, UTS, El) in the T6 condition, the dendrite fineness (DAS) and the level of microporosity. A correlation was found between the microporosity level, the local solidification time and solidus front velocity; this correlation allows to predict the porosity level in large aluminium castings (solidification times between 20 and 200 minutes). Quite expectedly, properties varied widely within the casting and the actual mechanical properties were much less than the "textbook values" based on measurements carried out on separately cast standard specimens. A correlation between the secondary dendrite arm spacing (DAS) and the local solidification time was in keeping with previously published data. Finally the conditions to obtain an acceptable finish on machined surface were determined.

Jan 1, 2014

By C. Tan, A. Putz, P. Lacombe, R. Kemp, M. Kaya, B. J. Huls, A. R. Laplante

"This paper concentrates on the four recent plant trials/ applications of froth washing. Results showed that improved metallurgical performance can be achieved with wash water. Increased froth cleaning yielded better upgrading, and some cases slightly improved recovery. Froth sampling and salt tracer tests supported the findings of froth washing tests.At Falconbridge, Ni grade increased from l.47% to 2.15% and recovery from 85% to 87%. At Eastmaque, final Au grade increased from 2.3 to 2.7 oz/st at a slightly higher recovery. At Les Mines Selbaie, Cu grade increased from 24.5% to 25.S% and Zn grade from 54.5% to 56.l%. At Zinc Corp. of America, average Zn grade increased from 55% to 56. 8% at the same recovery for a 45-day period. A number of plants in Canada and the United States have evaluated and/or now practicing froth washing. Wash water has now proved itself in some plants over several months of operation.INTRODUCTIONFroth washing in mechanical flotation cells offers a number of metallurgical (i. e. increased grades and/or recoveries) and economical (i.e. decreased transportation and smelting & refining costs) benefits. Fundamental development work in laboratory and pilot scales performed at McGill yielded encouraging results. (Kaya and Laplante, 1988a and 1989a). Since laboratory and pilot flotation performance can differ from full-scale due to differences in hydrodynamics, kinetics, and froth characteristics (e.g. stability, loading etc.), plant trials were essential to prove the viability of this technology."

Jan 1, 1990

By Yanping Xiao, Ton van Sandwijk, Gus Van Weert, Larry McHugh, Thomas Zabev

"All attempts to remove significant amounts of arsenic from enargite via neutral or reductive pyro routes have required operating temperatures between 600 and 700 º C, too high to propose an equipment development program. Operating at reduced pressures, or using hydrogen or elemental sulphur as a sweeping gas did not help to lower these temperatures. Admixing iron powder gave excellent results, but still required 700 º C. By fortuity, in recent experiments to produce tennantite from an enargite mineral sample, it was observed that enargite was completely converted to bornite, chalcopyrite with minor residual tennantite within an hour at 400-450 ºC. This is believed to be due to the presence of pyrite in the mineral sample treated. All earlier decomposition work appears to have been done on predominantly enargite (i.e. low pyrite) samples, or at high operating temperatures, ignoring possible reactions at lower temperature. The decomposition of enargite into iron substituted tennantite plus some bornite under evolution of liquid elemental sulphur, followed by further decomposition of this tennantite into bornite and volatile arsenic sulphides, appears experimentally feasible at these low temperatures and mimics described ore genesis pathways at > 250 ºC in saline solutions. We suggest two pathways to describe the observed experimental results:20 Cu3AsS4 + 12 FeS2 ???5 Cu10Fe2As4S13 + 2 Cu5FeS4 + 31 S(l)31 S(l) ???31 S(g) (evaporation)5 Cu10Fe2As4S13 ???10 Cu5FeS4 + 10 AsS(g) + 5 As2S3(g)"

Jan 1, 2014

By M. K. Aly

"ABSTRACTThis paper briefly describes the mining method proposed for the iron ore deposits in Wadi Shatti, western Libya. The iron ore produced will be used in the steel plant at Misurata on the Mediterranean coast. GeologyThe Wadi Shatti is located in the central part of western Libya. Flat iron-bearing sedimentary rocks are exposed with remarkable regularity in this valley. It occupies an area 200 km long by approximately 20 km wide trending in an eastnortheast direction between Jabal Fazzan in the north and Zel1af Sand Dunes in the south (Fig. I). Only a part of this valley has been ful1y explored by drilling on a 400- by 200-m pattern in an area of 18 km2 south of the town of Taroot. Farther to the south, no exploration by drilling can be done due to the presence of sand dunes .The iron-bearing bed is about 10to 15m thick, with a dip of 2 to 4 degrees in a southerly direction . The overburden consists mainly of clayey sandstones, 4 to 5 m thick, in the northern part, increasing to 35 m in the southern part. The iron ore bed consists of three different layers, from the floor upward: (1) Lower Reduced Ore (LRO), having a varying thickness of 1 to 7 m; (2) Magnetic Ore (MO), with a thickness varying from 4 to 12 m mainly in the central part of the area; and(3) Upper Reduced Ore (URO), with a bed thickness varying from 0 to 7 m."

Jan 1, 1980

By Arash Habibi

The FMC Westvaco Trona Mine is located near Green River, Wyoming and has an annual production of 4.5 M tons. The underground mine has three active development panels and one longwall panel. The mining horizon is about 500 m below surface and strata liberate methane. Three surface-based blowing fans provide ventilation air. A ventilation survey and subsequent analysis was undertaken and a simulation model developed. Air heating during winter is essential to prevent freezing of pipelines and to lesser degree, for miner comfort. Air at all three intake shafts is heated using gas-fired heat exchangers. A strata heat study was conducted in one of the active panels to determine rock attributes. Tests included in-situ measurements of rock thermal conductivity and geothermal gradient. Continuously methane monitors have also been installed in an active development panel?s return drift. Ventsim ventilation software was used to aid the heat and contaminant simulation study. An exercise was also undertaken to gain some understanding of methane contaminant levels throughout the mine. It was further used to determine an adequate surface intake air heating rate and consequently the minimum natural gas consumption needed for winter intake air heating at the mine.

Aug 1, 2013

By V. K. Srivastava1

Coal mine fires burn about 20?21 million tons of coal per year throughout the world, which not only results in loss of valuable coal reserves, but also cause serious environmental hazards over large areas. The famous Jharia Coalfield of Dhanbad, India is no exception; here a coal mine fire originally reported nearly a century ago is still continuing unabated in vast areas of the coalfield. In this paper, an attempt has been made to analyse high resolution multispectral thermal images of ASTER for mapping and delineating surface and subsurface coal mine fire areas of this coalfield. From the generated temperature gradient map, as well as from the surface temperature anomaly map, it has been possible to differentiate shallow and deep coal mine fire regions and other erroneous cultural features. It is observed that the coal fires are distributed mostly in the eastern part of the area, which has branched into two major coal fire zones: one along Lodna- Tisra-Bhulanbarari-Kujama-Jealgora Jharia and the other along the Kusunda-Kendudih area. The western fire zone is restricted in Dumra-Nadkhurkee-Jayramdih area. From ASTER thermal infrared data from 2006, the total affected area is estimated to be about 7 km2, of which the deep subsurface coal mine fire area is around 3 km2 and the shallow surface coal mine fire area is around 4 km2, as compared to 18 km2 coal mine fire area estimated in 1987 using Landsat TM thermal band data. In other words, the fireaffected region has decreased by about 50 % during the last 18 years. However, such decrease in coal fire area is seen in the central portion only, and has in fact increased in the south eastern parts of the Jharia coalfield. Study of Differential Interferometery images, generated from Earth Resources Satellite (ERS) synthetic aperture radar (SAR) tandem data has shown that the active coal mine fires are in general associated with low topography/subsidence areas.

Aug 1, 2013

By Dirk Claessens

The term ?cost? is too small when describing the destructive power of safety incidents for mining companies. Breaches in employee or environmental safety are felt way beyond the bottom-line: human life can be taken; ecosystems tarnished; the ire of peoples, media and government inflamed; significant halting of production; and high levels of legal and financial challenges. According to a recent survey of Mining executivesi, ?ensuring workforce safety? was the most important issues identified above any other, with a plurality of 31 percent, reigning above capital projects, product efficiency, and equipment reliability. We accept that safety is a most paramount issue, yet for many reasons we keep approaching the problem the same way we have in the past. We need to stop doing the same things decade over decade and try something new. New innovations are significantly changing the fundamentals of how mining companies explore, excavate, produce, refine and distribute their valuable commodities. Technologies such as visualization, analytics, location awareness, and gaming simulation are making these enterprises smarter. Now, attention turns to an area we?ve long held as integral to our business: safety. By using the same breakthrough technologies that are changing our business, we can now boldly imagine ? and credibly strive for ? a world of zero incidents.

Aug 1, 2013

In the last 30 years numerous mining plants have been developed in North America but only a handful of these have required freezing the area where the shaft was sunk. The most recent mine shaft to be sunk using this technique is located on an island off the coast of Louisiana. The project required the input and skills of numerous people in several companies, including the owner, engineers and contractors. The Cote Blanche installation is one of several mines in the area which extract salt from a dome which extends under the Gulf of Mexico. The geology of this area is, however, markedly different from others in the region because there is approximately 460 ft of water logged soil above the salt dome. Because it is not possible to sink a shaft in ground that is this soft, the overburden where the shaft is located must be frozen before excavation can take place. The Cote Blanche mine is a producing facility which was built in 1958 by the Carey Salt Company. The original facility included a 14 ft diameter production shaft and a 7 ft-8 in diameter service/ventilation/escape shaft. This system was installed by The Cementation Company. In 1996 the owner decided to improve both the mine ventilation and production hoisting system by installing a third shaft. This shaft would be designed to extract 650 tons per hour from a depth of 1600 ft and provide 500,000 cfm of ventilation to the mine at a maxium design pressure of 4 in WG. These parameters resulted in a requirement for a 16 ft finished inside diameter concrete lined shaft and a headframe designed as a pressure bulkhead. Because the mine would operate from one level only, the most efficient hoisting system for the application was determined to be a ground mounted koepe running on rope guides. With these criteria fixed Cote Blanche embarked on a program which would see construction start in June 1998 with the first salt produced in February 2001 at a cost of $US18M. The major players in the design and construction were G.L. Tiley & Associates Ltd., BLM Bharti Engineering, Freezewall Inc., Phillips Mining, Geotechnical and Grouting Inc., Don Hart Consulting and Dynatec International.

May 1, 2002

By M. Thérien, M. Rémillard

"Data from two industrial plants are treated by mass balance package BILMAT. The first application concerned a base metals/precious metals (PM) producer and the second, implementation of a hydrocyclone for the recovery of iron chips in the granite industry. Also LOTUS 123 software can easily be adapted for laboratory test mass balances using an IBM-PC computer. INTRODUCTIONThe present paper deals with two different BILMAT program applications. The first application concerns a copper-zinc-gol d-sil Yer producer based in North-western Quebec and the second, concerns the iriplementation of a hydrocyclone for the recovery of iron chips in Quebec granite company.Afterwards, we deal with some LOTUS 123 software applications for laboratory test mass balances using an IBM-PC.1. Base metal and P.M. producerNoranda Inc, Mattagami division, which operates mines in North Western Quebec, produces copper and zinc concentrates from a sulphide ore. Small amounts of gold (0,34 g/t) and silver (20 g/tl are present. At the time of the study, only 30% of the silver content was recovered in the copper concentrate. The main objective of this study is, to evaluate the metallurgical behaviour of silver in the flotation circuits, to increase its recovery in the copper concentrate and therefore to improve its final economic value. It is then worthwhile to identify the silver bearing minerals and to determine the critical flotation stages where they are lost. The methodology proposed is based on the coupling of a mineralogical study and a detailed mass balance ca1cu1ation in the flotation circuit performed using the BILMAT mass balance package (1, 2, 3).The results are discussed with respect to the distribution of silver in the circuit. The recoveries obtained at the various separation stages for the minerals present in the ore are also discussed."

Jan 1, 1987

By J. D. Gillaspie, D. T. White

"Sulphuric acid atmospheric leaching of nickel saprolite / garnierite ores was proposed in the early twentieth century, prior to the development of the pressure acid leaching process for limonite ores. Sulphuric acid leaching with alkali addition for iron precipitation as jarosite has been considered periodically since the early 1970s, shortly after the development of the jarosite process for iron control in zinc refining. In the late 1990’s a series of flowsheets were proposed and tested involving simultaneous atmospheric leaching, iron precipitation and acid regeneration. These were considered particularly suited to sequential leaching of limonite and saprolite ores. A number of laterite sulphuric acid leaching processes utilising this chemistry have been put into commercial operation. Similar sequential leaching flow sheets involving precipitation of iron as goethite were also developed and piloted. This paper will firstly describe some of the important historical developments of both the jarosite and goethite processes. It will then provide descriptions of the commercialised processes involving alkali jarosite/alunite precipitation, with special emphasis on the downstream impurity removal requirements necessary for efficient recovery of nickel and cobalt from solution.INTRODUCTION This paper is a summary and extension of previous works with which the authors have been involved, on the subject of sulphuric acid leaching of nickel laterites (Adams, et al., 2004), (Liu H. , Gillaspie, Lewis, Neudorf, & Barnett, 2004), (White, Miller, & Napier, 2006), (White, 2009), (White & Gillaspie, 2013), (White & Gillaspie, 2015). Some of the historical developments of both the jarosite and goethite leaching-precipitation processes will be described, followed by a description of the commercialised sequential nickel laterite leaching processes, involving alkali jarosite/alunite precipitation and acid regeneration, with a comparison to the equivalent goethite based processes. These will include Jarosite Atmospheric Leaching (JAL), Goethite Atmospheric Leaching (GAL) and combined Pressure Acid Leaching – Atmospheric Leaching, termed EPAL®. There will also be an explanation of the downstream impurity removal requirements necessary for efficient recovery of nickel and cobalt from solution."

Jan 1, 2016

"There are a number of disciplines in the minerals industry for which concern has been expressed regarding the sustainability of human capital. The boom-bust cycles that occur in the industry, the trend in tertiary education towards consolidation or in some cases cessation of minerals related programs and the increasing frequency of fly-in fly-out operations can all contribute towards a decline in the number of professionals with basic skills in process mineralogy. This paper describes approaches taken by the authors to incorporate process mineralogy into three levels of education, namely undergraduate, recent graduate and experienced professionals. The primary objective in designing the learning activities is the development of authentic learning experiences that provide participants with relevant skills in process mineralogy. Selected examples of approaches used by other education groups globally to address this issue are also provided.INTRODUCTIONThe boom and bust cycle of the mining industry has trickle down effects in tertiary education in terms of the ability of universities to consistently provide high quality graduates with relevant skills. When the commodity price surged in 2002 skills shortages in critical resource related professions were reported and despite investment in skill development there was a view from employers that not enough young people were graduating from relevant education programs (PricewaterhouseCoopers, 2012). At the time this signalled positive growth for engineering disciplines catering to the mining industry, however during the downturn cycles, most recently since 2012, graduates exiting from the discipline can find employment difficult and this contributes to reduced enrolments in subsequent years. From an AusIMM (Australasian Institute of Mining and Metallurgy) members’ employment survey conducted in 2013, more than half of the graduates exiting from disciplines related to mining and minerals were not confident of finding employment (AusIMM, 2013). In the long term the concern is not only how to sustain enrolment and graduate numbers but also to provide the opportunity for students to acquire the professional skills that they require to make them attractive to industry.Maintaining and sustaining core competencies in the minerals discipline is an ongoing challenge. There have been a number of recent papers on this issue presented at international conferences (e.g. McCaffrey et al, 2014; Drinkwater and Napier-Munn, 2014) and there is general agreement that one of the ways in which the deficit in foundation concepts can be addressed is through workplace development. Drinkwater and Napier-Munn (2014) presented data from a survey of industry professionals that indicated that more than 90% of respondents undertook on average 30 days of training each year of which approximately 5 days was professional short courses."

Jan 1, 2016

By Corby G. Anderson

"Laboratory testing using industrial electrowinning solutions was performed to determine the best Faradic cell efficiency for copper cathode recovery. The variables tested were solution flow rate, recycle ratio, reagent addition combinations of guar and thiourea, and addition amount of acid mist suppressant CAL FAX DBA-70. The ideal flow rate was determined to be 37.85 litre/min. Additionally, the ideal recycle ratio was determined to be 10:1. The reagent addition scheme from testing which showed the highest efficiency was with 680 g/tonne guar of cathode copper won and with 135 g/tonne thiourea of cathode copper won. These values for reagent addition only reflect the best efficiency and should not be assumed to be the best reagent concentration for copper purity. The amount of foaming agent that showed the best efficiency was the test with 2 ppm of foaming agent. Again this amount of reagent is based on efficiency and should not be taken as the amount of reagent that does the best acid mist suppression. Additional proprietary surface characterization work indicates these additives may have enhanced the cathodic reduction surface morphology of some noble minor impurities. Subsequently, these operating parameters were introduced into the plant operation and proved successful after their implementation.BACKGROUNDCopper electrowinning has become a dominant technology for the production of marketable high grade copper cathode products. The literature is robust with applications, optimizations, additives and developments in this field (e.g., Classens & Harris, 1990; Pfalzgraff, 1999; Tozawa, Su, & Umetsu, 2003; San Martin, Otero, & Cruz, 2005; Houlachi, Edwards, & Robinson, 2007; Romero, Avila, Fester, & Yacher, 2007; Marsden, 2008; Beukes & Badenhorst, 2009; Vainio & Weatherseed 2009; Bender, 2010; Joy, Staley, Moats, Perkins, Uhrie, & Robinson, 2010; Khouraibchia & Moats, 2010; Moats, 2010; Rutledge & Anderson, 2015).Tests of forty hours duration and at room temperature were performed for this project using samples of actual industrial electrowinning solutions. These industrial solutions were comprised of 60 g/L Cu plus 65 g/L Ni, 3 g/L Fe, and 30 g/L free sulfuric acid. Other confidential minor impurities were also present including some solubilized precious metals. The testing apparatus utilizing stainless steel anodes and cathodes is illustrated in Figures 1 and 2."

Jan 1, 2016

By M. J. Brodie

"The decision to proceed with mine decommissioning, generally involves a number of complex and independent factors. These factors, including potential for re-opening, legal requirements, contingent liability, asset depreciation, due diligence, and public relations are discussed in the context of the financial implications on a net-present- value basis. It is concluded that the decision to delay mine decommissioning is commonly not in the best financial interests of the mine operator. Some measures to reduce decommissioning costs and expedite the process are presented.IntroductionThe primary audience for this paper is mining executives, although it should be of interest to all professionals involved in the planning and carrying out of mine decommissioning. Historically, mines were abandoned, not decommissioned. Then, as decommissioning became required, it was assumed that salvage revenue would pay for decommissioning. During the I980s, it became apparent that mine decommissioning costs would exceed salvage revenue for nearly all sites, and that a substantial net cost for decommissioning would be realized for some sites. Throughout this period, the approach to decommissioning has evolved through the sequential addition of measures to meet the increasing regulatory burden. This has resulted in a process in which the elements of decommissioning may not be optimized with respect to each other for the most favourable net present value to the corporation. Additional considerations which are not specific to mine decommissioning, such as environmental policy, due diligence and public relations, may now come to bear on the decision-making process.This paper addresses the issue of mine decommissioning as a three-step process. The first step involves identification and evaluation of all of the issues that relate to mine closure, the most importantof which is the potential for re-opening of a mine. Assuming that it is decided that a mine is unlikely to re-open, the second step is to determine when to carry out the decommissioning work. This aspect is examined through a net present value (NPV) approach. Finally, details regarding who does the work and how the various tasks are divided up must be resolved.Every mine is a unique concentration of minerals at some specific location, hence the development, operation and closure of a given mine must be regarded as a special case. Superimposed on the site-specific considerations are the size, history and financial status of the associated corporation."

Jan 1, 1995

By J. Bouchard, R. del Villar, A. Vazirizadeh

"Industrial flotation is a continuous and often multistage process, where particles of a given mineral species (usually the targeted one), present in different sizes, encounter a large amount of gas bubbles (normally air) to produce mineral–bubble aggregates, which are removed from the flotation device (cell or column) as a valuable product (concentrate). The bubble content inside the cell is characterized by the prevailing hydrodynamic conditions (known as gas dispersion variables), which in turn are known to influence the flotation performance. Although most researchers and practitioners agree that the relationship between the hydrodynamic variables and flotation performance exists, the lack of an adequate method foronline measuring the average bubble diameter has prevented such studies.The aim of this study is to apply appropriate hydrodynamic variables for flotation kinetic modeling (as a key feature of flotation performance) for a given introduced particle size distribution (PSD). In this regard, experiments were conducted in a laboratory flotation column (5.6 cm internal diameter for a total height of 650 cm), and mixtures of quartz (hydrophilic gangue) and talc (naturally hydrophobic mineral), classified in four different size fractions. The correlation between the flotation rate constant and given hydrodynamic variables were analyzed. Results suggest that the relative importance of hydrodynamic variables for flotation rate modeling depends on the PSD. Finally the suggested hydrodynamic variables for each of the various particle size-classes considered were used to produce single variable models for the flotation rate constant. INTRODUCTIONIndependently of the prevailing flotation conditions, the mechanisms for bubble-particle aggregation and the residence time of the phases inside the device must also be considered. In this regard, one of the most used approaches to represent the overall flotation process is as a pseudo-chemical reaction between a particle and a bubble, whose rate (at a given time) is proportional to the amount of remaining floatable species. The proportionating constant is called the kinetic constant or the flotation rate constant."

Jan 1, 2016

By G. Sperlins

"IntroductionBrenda Mines Ltd. is a low-grade open-pit mining and milling operation located near Peachland, B.C. Brought into production in late 1969, the plant treats an average of 30,000 tons per day of an ore that contains 0.130% copper and 0.030% molybdenum.The operation is divided into six areas of responsibility, namely the mine, mill, plant, accounting, industrial relations and purchasing /stores departments.The purchasing and warehousing area handled in excess of 11,000 items valued at $31,000,000 in 198J. Over and above this, the warehousing area issued in excess of 74,000 line items valued at $15,000,000 during that same period.Materials Management- DefinitionWhat is meant by the term ""Materials Management""? Reference to the dictionary will reveal that a material is ""that of which anything is composed or may be constructed; the tools, instruments, implements', etc. for doing something"". Management is defined as ""the act, or manner of managing; the skillful use of means to accomplish a purpose"". Presumably combining these words defines materials management.Of greater importance are the materials managers who will carry out the function. At Brenda Mines Ltd., all employees and suppliers contribute to the materials management function. Each has a specialized knowledge of the materials used in his field. Each has a different view concerning the use and description of the same material. The key is to focus this knowledge so as to make the materials management system useful to everyone."

Jan 1, 1982

By Takao Oishi, Go Ohara, Toru Kitazaki, Masahiro Tanaka

"The High Pressure Acid Leach (HPAL) plant for nickel-cobalt mixed sulphide production at Coral Bay Nickel Corporation (CBNC) in the Philippines has been in operation since 2005 with a capacity of 10,000 t/year of nickel. Subsequent to the commissioning of the second plant in 2008, the production capacity increased to 22,000 t/year of nickel (Llerin et al., 2011). CBNC’s annual nickel production reached more than 24,000 tons of nickel in 2014. The concepts to achieve this capacity are the high availability and the reciprocally flexible operation of both plants. The availability depends on some factors, such as the control of impurities in the process and the equipment condition, to mention a few. In the HPAL process, it is not only the autoclave operating conditions that affect nickel extraction but also the impurities in the ore greatly influence it. The major element in the ore is iron and most of this iron is precipitated as Fe2O3, while the rest remains as Fe2+ or Fe3+ sulphate in solution. These ions in solution reduce the availability, so it is important to control the formation of iron ions by controlling the impurities in feed ore as well as the HPAL conditions. This paper presents the general HPAL process and the behaviour of impurities, focusing on iron behaviour in the HPAL process.INTRODUCTIONCoral Bay Nickel Corporation ProfileCoral Bay Nickel Corporation (CBNC) was founded on April 2002, as a joint venture of four companies; namely, Mitsui Corporation (18%), Sojitz Corporation (18%), Nickel Asia Corporation (10%) and Sumitomo Metal Mining Corporation (SMM) with a controlling stake of 54%. Aside from its capital share, Nickel Asia Corporation also supplies the ore and limestone for the High Pressure Acid Leach (HPAL) plant located in Rio Tuba, Philippines, as shown in Figure 1 (Tsuchida, 2008). The objective of the CBNC project is to produce 22,000 t/year (original design) of nickel and 1,500 t/year of cobalt, as sulphide, by the treatment of nickel laterite ore which is a low grade nickel oxide ore in the Philippines (Mines and Geosciences Bureau, 2014). The sulphide product has been exported as a raw material to the SMM Nickel Refinery in Japan for 30 years. The product of this plant, a mixed (Ni/Co) sulphide, is shipped to the SMM’s Nickel Refinery in Niihama, Japan. SMM Corporation provides the technology and management personnel to the plant. SMM Corporation also supplies the sulphuric acid, which is the main reagent for the HPAL process."

Jan 1, 2016

By R. G. McDonald

"High iron solution concentrations often result in the formation of basic ferric sulfate during the high temperature oxidation of sulfidic materials such as base metal and refractory gold concentrates. Consequently, the “Hot Cure Process” followed by limestone neutralization is required to facilitate subsequent processing and/or disposal of the leach residue. The present paper discusses strategies that can be employed to influence the composition and nature of the high-iron content leach residues produced during pressure leaching.INTRODUCTION Control of iron deportment in hydrometallurgical processing remains a key challenge for a range of reasons. Strategies generally relate to the control of conditions under which iron is optimally rejected (Demopoulos, 2009). Supersaturation provides the driving force for crystallization and this can be controlled by a number of factors that include (1) pH and/or Eh control, (2) the presence of matrix anions and impurities, (3) dilution, (4) complexation and dissociation and (5) manipulation of the rate at which the metal to be precipitated is released to solution. Each of these factors is impacted by temperature. Good control of crystallization is essential to the control of precipitate properties such as the degree of crystallinity, stability, particle size and quality which covers both the extent of impurity uptake and suitability of the precipitate for waste disposal. The quality and properties of iron precipitates in turn can impact downstream processing. It is the aim of this paper to discuss the generation of iron-containing residues produced during the pressure oxidation of sulfidic ores and concentrates and how the nature of these can be controlled to potentially facilitate further processing. A brief overview of several related topics will now be given and include, where relevant, discussion of work undertaken in our laboratories. In addition, brief discussions of selected process options that enable good control of iron rejection will be provided."

Jan 1, 2016

By P. R. Brito-Parada, G. Bhutani

"The physical processes occurring in flotation columns are very complex as they take place at different scales over a range of sizes and multiple phases. Column design and optimum operating parameters are usually obtained from empirical studies and although progress has been made on its numerical modelling, most column models rely on simplifications that do not fully capture the hydrodynamics. In particular, Computational Fluid Dynamics (CFD) models of the pulp phase in flotation usually assume the bubble population to be monodispersed. While this assumption may be reasonable in some situations, the polydispersed nature of the gas phase can have a significant impact on the predicted flotation rates.Techniques to model size distribution do exist in the literature and have been rigorously analysed in the past two decades for bubble columns, which are very similar to flotation columns from a hydrodynamics point of view. In fact, available CFD models of flotation columns are an extension of bubble column models, sometimes including additional equations for solids treated as passive scalars. This work focuses on the development of an efficient CFD model for flotation columns. The bubble size distribution in the column has been modelled using the Population Balance Equation (PBE), which is solved using the Direct Quadrature Method of Moments (DQMOM). Coupled with the PBE, the multiphase flow equations in the column have been modelled using the standard Eulerian–Eulerian approach. The solution of this coupled system has been made tractable in this work with the implementation of a highly parallelised adaptive-mesh finite element method. This powerful framework has been implemented in the open source CFD code Fluidity and it allows the carrying out of detailed simulations of flotation columns in 2D and 3D, with important implications for industrial column evaluation and design."

Jan 1, 2016

By J. P. Harrison, G. F. Gambino

"This paper examines unpredictability in the parameters governing hydraulic fracturing (HF) as used in stress amelioration for underground excavations, with the aim of showing how this unpredictability may affect design decisions. Using uncertainty models that are appropriate to particular levels of information and degrees of uncertainty, this paper demonstrates how these can aid in decision-making related to feasibility assessments of HF arrays for stress amelioration.Cave mining operations produce large underground voids and high stress concentrations around critical mine locations. These stress concentrations increase the potential for rock burst events. Although de-stress blasting has a long history for redistributing high stress concentrations, to improve safety and reliability HF is now being trialled as an alternative.Unfortunately the HF process is extremely uncertain, and so predicting fracture propagation geometry is difficult. Although the major parameters governing HF propagation have been previously identified, no indication has been given regarding the contribution that uncertainty in these makes to unpredictability in the overall HF system. Using simplified models of HF and referencing a recently proposed characterization of unpredictability, we relate unpredictability in the various governing parameters to the effect it has on strain energy density (SED) in the surrounding rock. Within these models we analyse SED as well as the stress intensity factor (KIc) when investigating the effect of parameter uncertainty and its influence on various crack propagation criteria (Sih & Macdonald, 1974). These models are applicable to unpredictability associated with the development of new fractures; the case of pre-existing fractures is the subject of on-going work.The paper will assess in greater detail the various governing parameters, and investigate the appropriate use of other uncertainty models. As a result, we will show how assessment of uncertainty in HF parameters can be used to both guide feasibility studies and determine the optimal allocation of resources to improve the final design."

Jan 1, 2015