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RISKGATE is an interactive online risk management system developed by the Minerals Industry Safety and Health Centre (MISHC; University of Queensland) to assist the mining industry in implementing continual improvement in management of major unwanted events, and so maximising health and safety performance. A comprehensive body of knowledge has been compiled from diverse mining industry experts for risk management of tyres, collisions, fires, isolation, strata underground, ground control open cut, explosions, explosives, manual tasks and slips/trips/falls. This paper presents an overview of the body of knowledge captured from diverse mining industry experts for the management of unwanted strata incidents, and explosions in the underground environment. This knowledge is divided into a series of initiating events within both topics (as listed) with further degrees of classification based on design, operation, and management concerns. Strata Underground Initiating Events: Explosions Initiating Events Loss of strata control at longwall face Fire or ignition in a sealed area Loss of strata control in outbye roadways Fire or ignition in an unsealed goaf area Loss of strata control in roadways under development Fire or ignition in an extraction face Loss of control of overburden and caving behavior Fire or ignition in outbye Loss of pillar system stability Loss of control of goaf edge in pillar extraction Fire or ignition in a development panel or first working Loss of strata control in shafts The system guides the user in generating substantive and leading edge controls to assist industry stakeholders in the design, management and reporting of organisational and regulatory compliance requirements. From a broader industry perspective, RISKGATE provides an environment for knowledge capture and knowledge exchange to drive innovation and best practice in the identification, assessment and management of risk. By capturing operational knowledge from industry experts, RISKGATE provides a cumulative corporate memory at a time of high personnel turnover in the coal industry.

Aug 1, 2013

By M. Falutsu

"The PSI-200 is a rugged, innovative, and easy to install on-stream size analyzer. Its calibration is simple and can be done on-line, during operation. Two measurements are displayed on the panel, which are expressed as percent passing a selected size, or as any statistical diameter. These two measurements are given as two continuous 4-20 mA output signals. Operation alarms are displayed on the screen or are given as digital output signals.The PSI-200 has been used in various applications at Lakefield Research. Particle sizes ranging from 10 µm to 450 µm have been monitored successfully, with an accuracy of 1- 2%. Having the size measured continuously and reliably, optimum conditions have been established for the grinding circuit, resulting in a superior quality in pilot plant testing.INTRODUCTIONThe challenge of any operating plant is to optimize product quality, maximize throughput and minimize operating costs. The importance of particle size measurement at a grinding circuit is well recognized. Monitoring continuously the particle size and keeping the product as uniform as possible is crucial to the whole mill operation regardless of the nature of the operation.Various techniques and instruments have been developed over the years attempting to give reliable on-line size analysis data. The operating difficulties and the reliability of these equipment still present major drawbacks and none of them proved to be widely accepted.PSI-200 is a relatively new on-line analyzer. The operation is simple and of low cost and the maintenance required minimal. It measures particle size and it displays two parameters of the solids size distribution, either weight fraction of passing a certain size or any statistical diameter. Two analog outputs can be sent to a process control system and through a supervisory control loop the correct action can be taken to maintain the desired particle size (perhaps adjust the feed rate to the grinding mill)."

Jan 1, 1993

By Stephen G. Hardcastle

Worldwide, metal mines are going deeper. For example in Canada there are six such mechanized mines planning production at 3000m (10,000?). Working at such depths challenges all aspects of mining including the provision of ventilation to supply an equitable working climate for personnel and machinery. This paper explores the overall challenges of supplying ventilation in Canada?s deepest mines and how the volumes required could be minimized. This is essential because it must be remembered that ventilation and refrigeration are not only costly items to supply, but the magnitude of their cost is also very sensitive to the volume supplied. For ventilation this is obvious because of the cubic relationship between volume and cost. In deep mines, the main function of ventilation is the removal of heat transferred from the strata and generated by the mining machinery, and the air volumes supplied are designed accordingly. The second consideration is the removal of other pollutants that could be harmful to humans such as diesel and explosive fumes. However, the need for ventilation at its present design levels could be reduced. This paper discusses the implications of such technologies as: teleremote mining and alternatives to diesel equipment on the magnitude of the volume supplied; ventilation-on-demand which recognizes ventilation as a costly and limited resource; plus other aspects, such as the benefits of controlled recirculation, local cooling, and heat rejection back to the strata to gain further advantage from new developments. Furthermore, this paper advances the need to be able to design ventilation systems more cost effectively and how such new advances as process simulators can be used in conjunction with ventilation simulators to explore the diverse options that could affect the air volumes required and provide more realistic economic data upon which to base design decisions.

May 1, 2003

"The ore currently being milled at Delnite is a high pyrrhotite ore with the gold intimately associated with the pyrrhotite. To get maximum recovery of the gold with the lowest reagent cost, it is necessary to keep the pH as low as possible In the laboratory the best results were obtained with a pH of 10 but in the plant it was found that a pH of 11 was the minimum practical pH. With the n1anual control it was difficult to maintain this figure.The Mines Branch had a conductivity probe (see Fig. 1), developed by Dr. G .G. Eichholz that they wished to try out in plant operation.On June 17, 1963, the probe with all necessary control equipment was installed in the regrind circuit (see Fig. 2) at Delnite Mines. Crushed quick lime is fed at this point but it is also necessary to feed hydrated li1ne at two other points in the cyanide circuit in order to maintain the pH close to 11. 0 throughout the circuit. Only the feeding of the quick lime at the regrind mill was controlled in this test.One thing that concerned me with the operation of the probe was whether the reading on the probe chart would correspond to the pH. A look at the graph accompanying this paper will show that except for very minor variations the graphs of the chart reading and the pH reading are parallel. The upper graph shows that the pH reading and the lime titrations also correspond and that the cyanide titrations appear to have little effect on the pH reading.Table 1 gives the results obtained for the two months before and after the instal1ation of automatic control as well as the two months of control. Unfortunately there was a decided change in ore just after the automatic controls were removed. There was much less pyrrhotitc in the ore than usual thus changing the need for lime and cyanide."

Jan 1, 1964

By L. Long

Stirred milling of nickel laterites offers possibilities for improving liberation and selective size reduction of soft nickel-bearing minerals in laterites. Batch grinding tests were performed in a Netzsch LME4 stirred mill on siliceous goethitic (SG), goethitic (G), and saprolitic (SAP) nickel laterite samples (- 2000 ?m particle size) to evaluate the effect of stirrer speed, solid content, water salinity and grinding time. A fine mineral product (-38 µm) was used to evaluate the effect of selective grinding and Ni upgrade. The optimum grinding time for the highest Ni upgrade was 0.25 min, 0.1 min and 0.1 min for the SG, G, and SAP nickel laterite, respectively. A new feed (38-2000 µm) for each nickel laterite sample was prepared for batch grinding tests under the optimum grinding conditions. Upon grinding the 38-2000 µm feed, the - 38 µm product confirmed the effect of selective grinding and nickel upgrade. Size classification followed by stirred milling is a suggested process for Ni upgrade. The best Ni upgrade result was achieved on the SG nickel laterite among the three samples. The Ni grade increased from 0.85% to 1.37%, with 27.8% Ni recovery. Bottle roll leach tests showed that for SG and SAP samples selective grinding had no dramatic effect on Ni extraction due to the slow leach rate of hard mineral particles. Stirred milling of G sample increased the surface area of goethite, resulting in higher Ni extraction. Gravity concentration through a Knelson Concentrator was not effective in the further treatment of the stirred milling products either due to the poor operating conditions or due to the mineralogy characteristics of the feed samples. The energy requirement in the stirred milling was investigated. The first pass of the signature plots study is critical for the purpose of selective grinding, because the best result on selective grinding is achieved in the early stage of the grinding process.

Aug 1, 2013

By A. J. A. Janse

The Argyle diamond mine is located in the Kimberley region in the northern part of Western Australia at approximately 16°43'S, 128°23'E in subtropical bush/shrub savannah. The 46 ha (113 acres) pipe is situated in the Halls Creek mobile zone, which was cratonized about 1800 Ma ago and adjoins the Kimberley Block, a plateau upheld by Early to Middle Proterozoic rocks underlain by presumably Archean basement. The crater and upper pipe zones of the diatreme have been preserved within tilted and faulted strata of Middle to Late Proterozoic age. Its age of intrusion is about 1178 Ma. The diatreme rock is not kimberlite but olivine lamproite which was not recognized as a primary diamond host rock until 1978. The Kalumburu Joint Venture, a syndicate of local and overseas mining companies, started in 1972 to prospect the Kimberley Block with a modest annual prospecting budget of $125,000. Annual expenditure doubled each year and reached $1 million in 1975 after which CRA took over management of the newly-formed Ashton Joint Venture with an annual expenditure of $2 million (all figures are in current US dollars). The Argyle diatreme was found near the end of the eighth field season and after a total expenditure of $12 million. Annual production is about 34 million carats which places Australia as the world's number one diamond-producing country, although, because of the low value per carat, it is number four in terms of total annual value. The global cost required for a major diamond mine is between $300 and $400 million, with a discovery every 10 to 12 years. Because Canada contains large areas of prospective platform rocks underlain by Archean basement it is likely that a major diamond deposit does exist there. It is probable that it will be found before the end of this decade and exploration expenditure may be in the order of $100 million.

Jan 1, 1992

By Abdurrahman Tosun

It is very important for after blasting processes that muck pile fragmentation is predicted and controlled during blasting. Therefore, a significant research effort has been devoted to the development of mathematical equations that predict the value of average muck pile fragmentation. The specific charge parameter used in all of these equations is determined as the ratio of the total mass of explosives used to break a volume of rock. The length of blast surface and the row number of the blasthole are ignored in the calculation of the specific charge. However, in a blasting operation, blasthole geometry may result in additional material being impacted by a blasthole. This is due to effect shares of in both end sides of blastholes and the back region of blasting surface. In this study, a total of 14 blast tests, 8 at the first quarry and 6 at the second quarry of the Bati Anadolu (Western Anatolia) Cement Factory, were performed. In each study area blast tests were designed in the same direction continuously to provide stable structural properties of the rock. Therefore muck pile fragmentation depended on only specific charge values for each blast tests. Specific charge values were calculated according to both an average blasthole and also the total volume of material occurred as a result of blasting for each blast tests. During loading until the end of blasted material the front, the back, the arm off and the bucket off pump hydraulic pressure values occurred in hydraulic pistons of the loader were determined with a lot of data received for each blast tests. After that the relationships between specific charges values obtained according to two different methods and hydraulic pressure values of the loader were established with two correlations. The relationships between specific charges values obtained according to the total volume of material occurred as a result of blasting and hydraulic pressure values of the loader occurred as the best results especially the blasting operations that have the total length of blasting surfaces are short.

Aug 1, 2013

By Chris M. Healey

"Perhaps the single most significant variable in the evaluation of a mining project is the reserve estimate. Many parameters are considered when estimating reserves, among them geology. This paper examines the link between the quality of a reserve estimate and a good understanding of the geological controls for the deposit. A clear understanding of the geometry is essential to the accurate definition of the shape and size of the deposit. This includes the definition of any structural controls as well as the proper interpretation of the stratigraphy. Further when the distribution of grades is erratic and there is consequently a high nugget effect, there are significant problems in estimating the true grade of the deposit.Two Saskatchewan examples are presented, one with good knowledge of the controls and therefore good estimates of reserves, and the other with a poor understanding of the geology and resultant problems in deriving good estimates. In both cases the reserve estimates at various stages in the project development are compared to actual results from underground work. The first example is the Star Lake Mine where just about all the estimates were within 10070 of the actual on both tonnage and grade. The Laurel Lake deposit is discussed to show how problems in interpreting the geological data make reserve estimation very difficult. Laurel Lake has the additional problem of erratic grade distribution."

Jan 1, 1992

By Paul G. Dunn

Safe rapid drift development results principally in reducing exposure of underground workers to the working face. This reduction in exposure is not achieved until either the rock walls have been suitably scaled or sufficient support has been put in place. Rapid drifting enables quicker access to orebodies (increasing returns), higher production rates and a resultant lower cost of mining. The Mining Innovation, Rehabilitation And Applied Research Corporation (MIRARCO) has been developing technology and a methodology for safe rapid drift development within the underground metalliferous mining industry. In terms of rock scaling for underground metal mines, there is still considerable use of manual and mechanical impact rock scaling techniques. Two main issues result from this approach. The first is that in highly stressed or highly fractured ground, a decision has to be made as to when sufficient scaling has taken place. This is not always easy to do and hence operator judgment is a crucial element in this approach. During a baseline study of current rock scaling practices, a wide range of scaling practices were observed within five different underground mining operations; this demonstrates the difficulty inherent in the rock scaling quality decision making process. The second issue is related to the exposure of workers to freshly created rock surfaces. In manual scaling techniques this is unavoidable and despite the best scaling practices, accidents still occur. In an attempt to provide an alternative scaling technology, MIRARCO has been investigating highpressure water jet scaling for removing loose rock as part of the drift advance process. This technology not only provides a means by which scaling practices can be engineered (remove the loose material you want to in a given rock mass condition), it is also quicker and easily automated. Automating the scaling process removes workers from exposure to freshly created rock surfaces and also enhances the application of spray-on liners through improved adhesion of these support types to the rock surface. This paper describes the water jet scaling technology research and methodology for safe rapid drifting within the underground metaliferous mining industry and highlights the key issues and major drivers behind their continued development at MIRARCO.

May 1, 2004

By D. McConchie

The use of Bauxsol? (physically and chemically modified alumina refinery residues) to treat acid rock drainage (ARD), and sulphidic waste rock and tailings, provides new options for managing some intractable environmental problems at both derelict and active mine sites. Treatment of ARD waters using the Bauxsol technology shows that the effectiveness of raw Bauxsol material can be enhanced by including modest amounts of selected industrial minerals or common chemical additives. The type and amount of additive required and the amount of the blend needed to treat the water depends on the initial composition of the water and the target water quality; for some ARD waters, optimum treatment may require one or more changes in the type or amount of additive used. Maximum treatment efficiency can be achieved only when a balance is maintained between the rate of trace metal binding and the rate of change in water pH; adding treatment reagents faster than can be accommodated by the reaction kinetics will not result in more rapid water treatment. This paper presents the results for treating several ARD waters to illustrate the importance of blend selection and treatment procedure. Although treating ARD water is often necessary, this strategy treats the symptoms rather than the cause. The best permanent solution is to treat the sulphidic waste rock or tailings such that they do not continue to oxidise and produce acidic metal-rich leachates; sulphide oxidation needs to be stopped or slowed to a rate that can be accommodated by normal environmental processes. Capping lined impoundments is not a solution because all caps and linings will inevitably fail some time in the future creating a nasty surprise for some future generation. Adding lime is also less than ideal because the lime leaches from the treated material; treatment often appears to be effective for a few years and then fails. Bauxsol technology offers effective alternatives to conventional liming and capping procedures and Bauxsol blend application rates and procedures can be planned to ensure that no acidic or metal-rich water can ever escape from the site. Bauxsol can be physically mixed with the sulphidic mine wastes or it can used to form subsurface permeable reactive barriers, or both. Bauxsol treated waste rock and tailings can be immediately and effectively revegetated. In this paper we present leachate quality and plant growth rate data for several sulphidic waste rock and tailings deposits treated using the new technology.

May 1, 2003

By Erol Yilmaz

This poster presents results obtained from an experimental test set-up called CUAPS (curing under applied pressure system) allowing to assess the performance and quality of cemented paste backfill (CPB) materials. CUAPS can be used for carrying out a series of tests: one-dimensional consolidation, saturated hydraulic conductivity, pore-water pressure dissipation, and curing under uniaxial stress. The poster presents CUAPS testing preliminary results including uniaxial compression tests (UCS) and mercury intrusion porosimetry (MIP). It was demonstrated that CUAPS-consolidated CPB materials cured under time-dependent stresses provide higher UCS values than standard mould (undrained and unconsolidated) CPB samples. This may be explained by the release of excess pore water within backfill that gives rise to a significant reduction in the total porosity of fresh CPB materials prior to hardening and thus, to higher mechanical strength (UCS) gain. The results obtained from MIP highlighted a good correlation between CUAPSconsolidated and mould-unconsolidated CPB samples. MIP results were also related to UCS values in order to predict the final CPB mechanical strength.

Nov 1, 2008

By M. Roy, Y. Roux, R. McIvor

"La Compagnie Minière Québec Cartier at Port Cartier. Quebec, utilizes six parallel wet grinding open circuit ball mills to grind iron ore concentrate for the pellet making process. In an attempt to improve grinding efficiency, a mix of 605 25 mm (1 in.) and 405 38 mm (1 ½ in.) grinding balls was charged to mill D while the opposite mix was used in all the other mills. Because media costs were higher for mill D, it was necessary to find out if the smaller balls provided a net economic benefit. Therefore, a test program was undertaken to determine the relative efficiency of the charge in mill D compared to the other grinding mills. Mill F was chosen for comparative efficiency measurements.The first problem was to choose a suitable definition of grinding efficiency. In management's view, previous attempts to quantify milling performance using population balance modelling were ineffective because they were unable to relate breakage rate functions to grinding circuit economical in any meaningful way. Work index analysis was also not favoured because of a number of complicating effects, including the fineness of the feed and product streams and open circuit grinding.It was decided to adopt a recent innovative approach which had been successfully applied to closed-circuit ball milling. For ""functional performance analysis of ball milling"" (McIvor et al., 1990; McIvor et al., 1991), a size criterion is first chosen to define ""fines·' and ~'coarse particles"". In this case 45 microns (325 mesh) was chosen to distinguish fines from coarse material. The relative grinding efficiency of each ball mill environment would then be ~e cumulative grinding (disappearance) rate of coarse (plus 45 nucrons) material per kilowatt hour of energy applied to the coarse material in the mill, divided by the grindability (measured in the laboratory) of the coarse material in the mill feed.Because the disappearance rate of coarse particles is also the production rate of fines, the following equation can be written for the efficiency of the mill environment, Effe, as defined above:"

Jan 1, 1994

By Bryon Bisiaux, Walter Valery, Sonny Mwansa, George Amonoo, Adrian Dance

"Newmont Ghana Gold Limited’s Ahafo operation have been working with Metso Process Technology & Innovation (PTI) since early 2009 to increase mill throughput from a combination of controlled blasting practices and optimised primary crusher and grinding circuit conditions. For such Mineto-Mill projects, PTI’s methodology is termed Process Integration & Optimisation (PIO).Ahafo operate a SAG mill, ball mill and pebble crusher (SABC) circuit that processes a range of primary ore of varying hardness from different pits which is blended with soft oxide material. The PTI study focussed on ball mill limited material from the Apensu open pit.Following a benchmarking study of all blasting, crushing and grinding practices in January 2009, PTI recommended changes in both blasting and crushing conditions in order to generate a finer feed size to the SAG mill. Additional operating changes in the grinding circuit were recommended.A series of trials were conducted in November 2009 where three blasts were fired using a different blast design (hole diameter and explosive type) in the same area of the Apensu pit as the benchmarked material in January 2009. Top and bottom benches (or flitches) from each blast were sent exclusively to the grinding circuit and the material was tracked using PTI’s SmartTag™ system.The results from the six trials showed a significant increase in primary ore throughput at a reduced blend of oxide material. Ahafo have since standardised on these modified blasting conditions for all Apensu ore zones and have been able to sustain higher throughput compared to historical performance on similar material.This paper summarises the phases of the PIO project, the changes made in operating practices and the outcomes of the blasting trials that validated the predicted increase in mill throughput."

Jan 1, 2012

By K. Waters, A. Navarra, T. Grammatikopoulos

Strategic decisions to develop a mineral deposit are subject to geological uncertainty, due to the sparsity of drill core samples. The selection of metallurgical equipment is especially critical, since it restricts the processing options that are available to different ore blocks, even as the nature of the deposit is still highly uncertain. Current approaches for long-term mine planning are successful at addressing geological uncertainty, but do not adequately represent alternate modes of operation for the mineral processing plant, nor do they provide sufficient guidance for developing processing options. Nonetheless, recent developments in stochastic optimization and computer data structures have resulted in a framework that can integrate operational modes into strategic mine planning algorithms. A logical next step is to incorporate geometallurgical models that relate mineralogical features to plant performance, as described in this paper.

Jan 1, 2017

By Mark Richards

Highland Valley Copper is a large, open-pit copper mine in the southern interior of British Columbia. Reclamation has been in progress on the site since 1987. Some 6,300 hectares will have been disturbed at the end of the mine?s life, the majority of which will eventually be reclaimed. The establishment of vegetation and the development of a self-sustaining vegetative cover are the central components of the mine?s reclamation plan. The present vegetation-monitoring program for the reclaimed area represents a significant commitment of resources and only addresses a small portion of the site each year. In an effort to expand the area surveyed while improving the efficiency of the monitoring, the use of remote sensing is being investigated. Airborne multispectral imagery was acquired in the summer of 2001, and the results of the multispectral classification were compared to ground observations made during the routine 2000 and 2001 monitoring program. A thematic map with 17 vegetation classes was produced. Within the vegetation classes, there was a strong spectral separation between ? dry grasses? and ?legumes? with further separation according to their density. Green biomass could also be quantified remotely across a wide variety of vegetation types. During summer 2002, further aerial imagery was acquired in combination with a targeted ground-truthing program to determine characteristic vegetation types associated with recognized spectral signatures, which can be used in a supervised classification. It is anticipated that after some fine-tuning, it will be possible to shift the ground-sampling effort from areas where the aerial classification confidence is high to more complex areas.

May 1, 2003

By T. Donkin, B. Patterson, M. I. Guthrie, J. T. Ross

"Interest in the use of particle-based ore sorting has increased significantly with recent advances in sorting technologies and higher capacities per unit. Particle-based ore sorting has the potential to provide great value in processing lower grade ores from mines while delivering higher grades to the mill, as well as in upgrading waste rock into ore. Typically the focus is on the amenability of the ore to ore sorting and associated reductions in energy, water, and consumables utilization. However, layout significantly affects the installed cost of a processing plant, and the impacts on layout from fitting an ore sorting circuit into the plant plan need to be carefully considered. This paper examines processing plant layout considerations that play an important role in ore sorting projects, including additional crushing and screening requirements, transport of rejected material back to the waste stockpile (mine fleet requirements), and effects on the processing plant footprint. ¦ KEYWORDS Cold climates, Ore sorting, Plant layout RÉSUMÉ L’intérêt porté à l’utilisation du tri granulométrique du minerai a considérablement augmenté au vu des récents progrès réalisés en matière de technologies de triage et des capacités supérieures par unité. Le tri granulométrique du minerai offre une plus-value intéressante en termes de traitement du minerai à plus faible teneur extrait des mines ; il permet par ailleurs l’acheminement vers le concentrateur de minerai à plus haute teneur et la revalorisation des stériles dans le minerai. On met généralement l’accent sur la susceptibilité du minerai au triage et sur les réductions connexes en termes d’utilisation de l’énergie, de l’eau et de biens consommables. Cependant, l’aménagement physique de l’équipement a une incidence non négligeable sur le coût installé d’une usine de concentration, et les répercussions sur l’aménagement de l’installation d’un circuit de triage du minerai dans l’usine doivent être soigneusement examinées. Cet article étudie les considérations relatives à l’aménagement de l’usine de traitement qui jouent un rôle important dans les projets de triage du minerai, et notamment les exigences supplémentaires en matière de concassage et de criblage, le transport de matériau résiduel jusqu’à la pile de stockage des déchets miniers (nombre de camions requis dans le parc minier) et les effets sur l’empreinte de l’usine de traitement. ¦ MOTS CLÉS aménagement de l’usine, climats froids, triage du mineraiINTRODUCTION Ore sorting has been practised throughout history. An early report by Agricola in 1556 documents how metallic and non-metallic minerals were extracted from rocks by laboriously breaking them with hammers and picks and hand-picking selected material with higher grade (Hoover & Hoover, 1950). The concept has not changed, but sorting technology has evolved significantly over the last 20 years"

Jan 1, 2019

By T. Junne, L. Eltrop, S. Moreno-Leiva, J. Haas, W. Kracht

The energy systems of the future will be highly renewable. The flexibility that is consequently required can be provided with many options, the main ones being energy storage, transmission reinforcement, and demand side management. The role of the latter is explored for the copper industry, using the scheduling of maintenance services as an example of Solar-Paced Design - the coupling of energy demand with solar resource availability. We used a linear energy optimization model to define the minimum-cost configuration for a fully renewable energy system of a copper concentration plant under different scenarios for the scheduling of maintenance services. For the case we studied, (total) costs were 4% lower when the maintenance was scheduled in winter. We expect that exploring the potential of such Solar-Paced Design in the copper industry will allow new potentials for a more cost-effective full renewable energy supply of this critical industry. INTRODUCTION The mitigation of climate change requires a worldwide transformation of the energy system by the significant expansion of renewable energies and the electrification of various sectors and processes (Teske et al., 2015)(International Energy Agency IEA, 2018). Moreover, considering the decreasing costs of renewable energy technologies and the intensive use required to deliver the goals in the Paris Agreement, we can expect to have highly renewable energy systems in the near future. However, to rebuild and expand our energy systems, we need certain materials, including copper. Also, energy systems based on renewables are more copper-intensive than conventional ones (Kleijn, van der Voet, Kramer, van Oers, & van der Giesen, 2011). The mineral industry, in turn, needs clean energy to achieve a better environmental performance (e.g. solar energy for copper production (Moreno-Leiva et al., 2017)) and to avoid negative secondary effects induced by the strong expansion of clean technologies. But there is something else the minerals industry can offer in this bi-directional relation with energy systems.

Jan 1, 2019

NANA Accepts Mining ­ 1974 - Leadership presented mining option to people ­ Community meetings; recognized need for cash economy ­ 1979 - Poll shows consensus in favor of mine development ­ 1980 - Shareholders approve mining; Congress approved land selections

May 1, 2002

By D. B. Dreisinger, A. A. Gunaratnam

A pressure oxidation (POX)-hot cure (HC)-lime boil (LB) process is used in industry to recover silver from refractory gold sulfide ores containing minerals such as pyrite and arsenopyrite. Pressure oxidation is used to oxidize minerals and liberate occluded gold particles. As such, iron goes into solution and under acidic and high temperature conditions often precipitates as basic iron sulfate (BFS). BFS consumes excess lime during neutralization prior to cyanidation. Therefore, a hot cure stage is required to re-dissolve BFS back into solution. BFS re-dissolution consumes acid and produces ferric sulfate. In the presence of silver, these conditions favor the slow formation of silver jarosite. Silver jarosite is refractory to cyanidation, and must be broken down prior to cyanidation. This is done in the lime boil to produce a cyanide-soluble silver hydroxide. A study was conducted to investigate parameters that affect the precipitates that form in each stage of the POX-HC-LB process.

Jan 1, 2017

By S. Knapp

Inconel 600 pipes welded to Carbon-Steel are used in CANDU nuclear reactors. Fracture of these welded tubes would have important consequences in term of safety, and therefore their mechanical properties need to be better understood. In this study, the weld region was analyzed at various length-scales using optical microscopy, micro hardness testing, small and large scale tensile testing and digital image correlation (DIC). Large grains were observed in the weld region and smaller grains in the Inconel and carbon steel base metals. Micro-hardness profiles showed variations across the weld and through thickness and were justified in terms of residual stresses in the sample. Large tensile samples were extracted from the welded pipe and were used to identify the material in which fracture initiates. In addition, the local strains in each material were obtained using digital image correlation. Local stress-strain curves were built from the DIC data and compared to stress-strain curves obtained from miniature tensile samples extracted from the carbon steel, Inconel and weld regions. The results demonstrate the advantage of using DIC for extracting local material properties in dissimilar weld systems. Variations in the materials stress-strain curves thought thickness are also presented and emphasize the need for obtaining a complete map of the mechanical properties in the weld region for predictive models to be accurate. Preliminary fracture studies will also be presented.

Jan 1, 2011