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By A. Abdollahi

Modification of the silicon in Al-Si alloys can be performed by adding a very small amount of some elements like Na, Sr and Ca to alter the form of silicon from an acicular shape to a fine fibrous one. This modification results in a considerable improvement in mechanical properties especially elongation, Metallographic observations in A356 alloy indicated the degree of the modification with Na, Sr and Ca, They showed that the effect of Ca as a modifier is not as strong as is Na or Sr while Na is the most effective modifier, Although modifiers improve mechanical properties, they also increase porosity in castings, The reduced pressure test (RPT) and Tatur test showed that the increasing porosity with Na is the most and with Sr is the least.

Jan 1, 2004

By J. Dilbeck, J. K. Ratliff, T. Petrov, Z. Brown

"In efforts to improve dust control during deep cut continuous mining a supplemental atomizing spray system, mounted on 14CM15 continuous miner, has been designed and successfully implemented in a U.S. coal mine. The mine is 2.1 m (7-ft) high and uses a blowing curtain face ventilation system with 1.1 m (3.5-ft) curtain offset from the rib. The face ventilation design parameters were set to 9.4 m3/s (20,000-cfm); 4.2 m3/s (9,000-cfm) line curtain flow rate, and 3.8 m3/s (8,000-cfm) scrubber capacity. The performed in-mine measurements, before and after the implementation of the atomizing spray system, showed a significant decrease in the respirable dust levels at the operator place as well as at the return. The paper describes the supplemental water spray system design and performance supported by three-dimensional computational fluid dynamics (CFD) simulations and in-mine test data.INTRODUCTIONThe work on this project have started in 2015 with a study of the conventionally applied face ventilation layouts. The specific behaviour of the face ventilation system have been analyzed trough in-mine measurements and computer modeling of typical cut scenarios. An computer modeling methodology have been developed for estimation the respirable dust concentration (RDC) using tracer gas to RDC contour mapping, calibrated by a single point value, provided by in-mine measurement. Utilizing the results of this study the engineering staff of the mine designed and implemented a supplemental atomizing spray system to improve the dust control during the deep cut continuous mining. Today the atomized spray system is successfully applied demonstrating steady performance and a significant decrease in respirable dust concentration on the working places of the continuous miner (CM) and coal transporters (CT) operators as well as at the return air stream. Information about the applied type of spray nozzles provided by other researchers (Cheng, 1973; Dick et al., 1996; Organiscak & Page, 1998; Pollock & Organiscak, 2007) and spray system manufacturers (Spraying System Co, 2011–2018; Steinen Mfg., 2016) have been used in this project. CFD code and simulation approach validated in a study conducted in 2000-2014 have been applied (Turner et al., 2002; Wala et al., 2004, 2007; Petrov, 2014)."

Jan 1, 2019

By B. Dyck, C. Rodgers

ABSTRACT Cameco Corporation is revitalizing its Key Lake Operation uranium mill in northern Saskatchewan. The mill currently uses ammonia stripping in solvent extraction (SX) and ammonia yellowcake precipitation. As part of the revitalization, the company considered installing strong acid stripping in solvent extraction (used at its Rabbit Lake Operation), which would lead to using hydrogen peroxide for uranium precipitation. As part of the process evaluation, tests were carried out to study how the drying temperature in indirect fired dryers would affect the uranium peroxide yellowcake precipitate properties. This paper discusses the test work results, including the relationships between drying temperature and product reactivity with water, product colour, product grade, and energy input requirements.

Jan 1, 2012

By Alan A. Barton

Introduction The Little Long Lac mine is situated in the Thunder Bay mining district, township of Errington, Ontario. The mine is located on the south side of the most westerly bay of Little Long Lac. The property consists of 36 claims, which comprise some 1,400 acres. This group of claims was staked in August, 1932, by Tony Oklend and Tom Johnson, and, after surface sampling, was optioned by the present controlling interests, who diamond-drilled it during the winter of 1932-33. In early spring, a small steam-driven plant was installed, and shaft sinking commenced on June 1st, 1933. During the summer, all supplies are transported to the mine from Hardrock station, at mileage 18 on the Canadian National Railway line from Longlac to Port Arthur. At Hardrock, which is seven miles from the mine, the railway skirts a bay of Little Long Lac, and supplies are loaded directly from railway cars to scows. Two scows are used, of 30-and 45-ton capacity, respectively. A 36-ft. pointer, powered by a 35 h.p. engine, is used as a tug. A good winter-road has been cut out from Geraldton to the mine, for winter transportation. Geraldton is about two miles north of the mine, and is also located on the Canadian National railway. A hard-surface road is now being constructed for summer as well as winter use. Geology The Little Long Lac gold area covers the northern limits of a large synclinal structure, the contact of the Keewatin flows and sediments, striking about twenty degrees north of west, with the dip of the sediments varying from eighty degrees north to seventy degrees south, the average being around eighty degrees south. The vein worked by Little Long Lac Gold Mines occurs in massive sedimentary rock of about the composition of arkosic or quartzitic greywacke, and consists of a shear-zone up to fifteen feet in width, striking N.75°E. and dipping steeply to the south, which has been filled by numerous narrow, parallel quartz veins and. veinlets. These are well mineralized. with arsenopyrite, pyrite, and some chalcopyrite and stibnite, and carry considerable quantities of visible gold. They show more than one age of quartz deposition, the quartz being fractured and re-cemented. The arkosic rocks separating the veins and veinlets are also slightly mineralized with pyrite. Work to date has indicated the probability that the vein-shear is controlled by local drag-folding.

Jan 1, 1935

Sherwood?s Minto Project ? High grade copper copper-gold deposit ? Yukon Territory, Canada ? Development underway ? Permitted ? Production by mid mid-2007 ? 40 40-50m lbs Cu plus Au/Ag by by-products ? Parallel exploration program underway ?Discover more high grade resources ?But what kind of deposit is it?

May 1, 2006

By M. Drozd, M. Somppi, Z. F. Yamak

"Activated carbon is used to recover gold in solution from various gold circuit designs including carbon-in-pulp (CIP), carbon-in-column (CIC), and carbon-in-leach (CIL) processes; however, the characteristics and durability of the activated carbon can vary. Handling this medium poses challenges when fine carbon losses occur in the CIP, CIC, and CIL circuit discharge. Additionally, adsorbed gold on carbon fines can be lost to the discharge. The studies in this paper aim to standardize laboratory methods for testing activated carbon qualities specific to the gold industry. The investigation focused on size distribution, platelet content, wet attrition resistance, gold kinetics, and gold loading. The results demonstrate that a 96 h attrition test and a gold loading test form a basis for ranking carbon samples based on expected economic performance of the plant. ¦ KEYWORDS Activated carbon, Carbon attrition, Carbon ball-pan hardness, Carbon evaluation, Carbon fines loss, Carbon turnover RÉSUMÉ Le charbon actif sert à récupérer l’or en solution dans diverses conceptions de circuits de broyage d’or, notamment les procédés de charbon en pulpe (CIP, de l’anglais carbon-in-pulp), de charbon en colonnes (CIC, de l’anglais carbon-in-column) et de lixiviation au carbone, ou charbon au lixiviat (CIL, de l’anglais carbon-in-leach). Toutefois, les caractéristiques et la durabilité du charbon actif varient. La manipulation de ce milieu pose des problèmes dès lors que se produisent des pertes de carbone à grain fin dans la décharge des circuits CIP, CIC et CIL. Par ailleurs, l’or adsorbé sur les fines de charbon peut se perdre durant la décharge. Les études réalisées dans le cadre de cet article visent à normaliser les méthodes de laboratoire pour tester les qualités du charbon actif spécifiques au secteur de l’exploitation aurifère. L’étude portait sur la composition granulométrique, la teneur des plaquettes, la résistance au frottement humide, la cinétique de l’or et l’adsorption de l’or, à savoir la capacité du charbon actif à adsorber l’or sur une période spécifique. Les résultats ont montré qu’un test de frottement de 96 heures et un test d’adsorption de l’or constituaient le fondement d’un classement des échantillons de carbone du point de vue économique en vue de trouver l’échantillon générant le meilleur rendement des usines. ¦ MOTS CLÉS charbon actif, dureté de la batée des billes de carbone, évaluation du carbone, perte de fines de charbon, renouvellement du carbone, résistance au carbone INTRODUCTION The use of activated carbon for gold extraction is among the most common processes in modern gold-milling plants. Although gold losses are inevitable in the milling process, operators often focus on reducing gold loss to tailings. One focus area that is important in gold recovery is optimizing the use of activated carbon and examining potential changes to realize improved economics for carbon-in-pulp (CIP), carbon-in-column (CIC), and carbon-in-leach (CIL) processes. Granular activated carbon (Figure 1) is widely used for gold extraction from slurries containing gold-cyanide complexes. This activated carbon—produced from charred coconut shells—is well suited because of its adsorption kinetics, gold-loading capacity, attrition resistance, and ability to be reactivated. The extraction process using activated carbon technology involves adsorbing gold from an aqueous leachate; the gold is dissolved using a cyanide salt and consequently a dicyanoaurate(I) ion (Au(CN)2–) is formed, as noted in equation 1."

Jan 1, 2019

By Viraj Parekh, Kinnor Chattopadhyay, Sina Mostaghel, Xiao Zhang

Electric arc furnace steelmaking is a dominant approach in North America and controlling EAF emissions is a key issue today because of stringent permit limits imposed by various regulatory bodies. In the present study, an attempt has been made to mathematically model EAF emissions, and use the models as a predictive tool for fine tuning the process. CFD modelling has been used to model various fume release scenarios, and optimize the exhaust conditions for maximum capture. Thermodynamic calculations have been used to analyze various chemical reactions which lead to the emissions of hazardous air pollutants with special emphasis on Zinc, Lead and Manganese.

Jan 1, 2015

By Etienne S. Bieler

Mr. Chairman, Ladies and Gentlemen, I come to you tonight distinctly as a physicist, not as a geologist or a mining man. My experience in applied geophysics has been short, and I do not doubt that many of you have a much larger acquaintance: with the subject than I have. A little over a year ago, the firm of Alderson, MacKay & Armstrong decided to investigate the possibility of developing a new method of electrical prospecting suitable to our northern Quebec and northern Ontario conditions, and asked me to take up the work. A preliminary survey of existing literature convinced me that the field of induction methods was most promising. I wish to give you some account of the work carried on last summer in the Rouyn district in this connection with the very able assistance of Mr. H. G. I. Watson. Geophysical methods of prospecting can be divided generally into four classes: magnetic, electrical, gravitational, and seismic. Each class depends on the existence of a definite property in which the valuable mineral to be discovered differs materially from the surrounding rocks. In the four classes, the property will be, respectively, magnetic permeability, electrical conductivity, density, and elasticity. By far the largest differences occur in the case of electrical conductivity, where it is not rare to find ratios of the order of several millions, or even billions, between ores, sulphide ores especially, and the surrounding rock. Hence the sensitiveness and delicacy of electrical methods. Of these four classes, only two, the electrical and the magnetic methods, have been put to extensive practical use in the discovery of metallic ores. The other two classes are important mainly in connection with oil detection.

Jan 1, 1928

By CIM Mineral Resource, Mineral Reserve Committee

These Leading Practice Guidelines for Mineral Processing (LPGMP) were prepared by the Sub-Committee on Leading Practice Guidelines for Mineral Processing. The Sub-Committee reports to the Executive Committee of the Canadian Mineral Processors (CMP) which is a Technical Society of the Canadian Institute of Mining, Metallurgy, and Petroleum (CIM) and incorporates those members of the CIM who are concerned with the processing of mineral deposits. The LPGMP covers the involvement of mineral processing professionals, referred to as Practitioners in this document, in providing inputs to the estimation of Mineral Resources and Mineral Reserves and providing technical content for internal reports as well as public reports on mineral projects as required under National Instrument 43-101 Standards of Disclosure for Mineral Projects (NI 43-101). The LPGMP supplement the CIM Exploration Practice Guidelines (2018) and the CIM Estimation of Mineral Resources and Mineral Reserves Practice Guidelines (2019) which are referenced in Companion Policy 43-101CP to NI 43-101 and recognized internationally. The LPGMP consist of 3 sections: • Principles of Process Support in Mineral Resources and Mineral Reserves Estimation; • Appendix A – Use of Supporting Studies in Process Evaluation and Assessment for NI 43-101 Documentation; • Appendix B – Glossary of Terms Relevant to the LPGMP. The LPGMP deal primarily with the description of leading practice as it applies to the mineral processing and extraction of base metals, precious metals, and other mineral products by the application of mineral processing technology. Other commodities may be considered with future updates of these guidelines. It is expected that this is a ‘living’ document and that these guidelines will develop in the future to address the requirements of the mining industry, investing public, and mining professionals involved. Clarifications and changes to these guidelines will be done under the guidance of the Executive Committee of the CMP.

Nov 25, 2022

Background ArcelorMittal?s (formerly QCM?s) Port Cartier iron ore pelletization operations 2 side-by-side induration furnaces each producing 578 t/h of cured pellets Firing No. 6 fuel oil and coke breeze (in bed) Very large heat losses to be addressed primarily by gas recirculation

May 1, 2011

By E. Heikkinen, J. Suikkanen, T. Siren, J. Valli, M. Hakala

Diametrically faced borehole breakout observations are a fairly good indication of magnitude of the secondary stresses acting perpendicular to the borehole. In cases of low in situ stresses, where borehole breakouts are not observed naturally, it is possible to increase the prevailing stress state around the borehole by increasing the rock temperature. When the temperature is increased sufficiently, thermally induced borehole breakouts will occur. By implementing the temperature increase in boreholes located at excavated tunnels, it is also possible to study the effect of the near-field stresses caused by the excavation. The near-field stress state changes as a function of borehole depth, thus increasing the information available from experiment. To study the feasibility of this proposed low cost method, a Borehole Thermal Spalling (BTS) experiment was executed in ONKALO Underground Rock Characterization Facility, in Western Finland in 2014. The first borehole pilot test with the method was conducted in ONKALO at the POSE niche in already at May 2010, with the second pilot test following in August 2010 at Äspö HRL. The major objective of the experiments was to define the trend of the maximum in situ stress component, while also providing knowledge of the in situ spalling strength of the ONKALO rock mass. The stress state in ONKALO is nearly isotropic in horizontal layer, causing problems for the use of more traditional stress measurement methods. With boreholes heated over long interval, the weakest rock parts are observed to fail, thus providing statistical confidence. For these reasons, continuous test sections have an advantage in ONKALO, compared to spatially limited stress measurement methods such as overcoring and hydraulic fracturing. The BTS experiment is conducted in 9 meter deep vertical boreholes located at the POSE niche, situated -345 m depth below the ground surface. The boreholes used within the BTS experiment are located in migmatitic granite, in an experiment area where the surrounding stress state and the rock strength are fairly well known. The prior knowledge of the stresses is favourable for the experiment, as it requires careful planning and iterations to determine the appropriate heating power domain. Too low heating power will not be sufficient to cause borehole breakout, while too high heating power causes breakout in all directions thus making determination of stress direction hard or impossible. The initial state of the borehole and induced borehole breakouts will be monitored using acoustic televiewer logging (ABI) and optical borehole logging (OBI) imaging techniques. Fracture mechanics modelling is used in planning of the experiment, also in back-analysis to link the observed breakout angle to stress state. Both the pilot test in 2010 and BTS test in 2014 resulted in similar borehole breakout direction. The results are in line with so called EDZ & VT1 stress interpretation, revealed the maximum horizontal component bearing the magnitude of 21.5 MPa, with the trend of 166°.

Jan 1, 2015

By I. Farr, H. Wittens

"In 1989 and 1990 abnormally high levels of arsenic in ore from the Thompson Open Pit Mine threatened Manitoba Division's electro-nickel production. The paper will discuss our development of a flotation process to separate pentlandite and gersdorffite (the prime nickel and arsenic bearing minerals).The presentation will focus on the development of the process from conception, through lab and plant test work, to plant optimization and full scale production. The paper will conclude with the benefits and cost of the completed project.INTRODUCTIONRejection of arsenic from nickel sulphide ores was not a primary concern in the Manitoba Division until 1989. At that time increased production in the Thompson Open Pit mine, which contains high arsenic ore zones, resulted in excess amounts of arsenic in the Thompson Refinery affecting electro-nickel quality. This problem was resolved through extensive efforts by Mill personnel. The purpose of this paper is to familiarize the reader with- the Thompson Mill.- the mineralogy of the Thompson orebody.- the evolution of Ni/As separation in the Mill.- the metallurgical impacts of the separation on the Mill.- the importance of the separation to the Manitoba Division."

Jan 1, 1991

By V. Barranco, K. Yliniemi, A. Hubin, B. P. Wilson, D. Janas, M. Lundström, P. Hannula

Typical copper electrorefining electrolyte contains tens of grams of copper, some nickel and a wide variety of impurities. Some of these impurities comprise trace amounts of dissolved precious metals like Ag, Pd and Pt that currently are not fully exploited. This study presents an electrochemical method to recover precious metals via a combined electrodeposition-redox replacement (EDRR) process, where energy is used only to deposit copper during the ED-step, while the RR-step relies on the spontaneous replacement of copper by the precious metals (i.e. cementation). In order to conduct the recovery successfully, process parameters such as deposition potential (EDE), deposition time (tDE), redox replacement time (tRR) and the number of cycles (n) was adjusted. Investigations performed in synthetic electrolyte (40 g/L Cu, Ag = 10 ppm) proved the possibility to recover a high purity silver. Short deposition times (tDE) were found to result in small Cu particles that provided a suitably high surface area for silver cementation. In addition, experiments performed in real industrial electrolytes containing 44 g/L Cu and 54 ppb Ag (Boliden Harjavalta, Pori), demonstrated that EDRR could attain Ag recoveries of between 46–67% in an energy efficient, additive-free manner. INTRODUCTION The raw materials used in the state-of-art primary and secondary copper smelters contain mainly base metals, but also notable amounts of Ag, Pt and other precious metals. These valuable metals distribute mostly into the copper matte during the pyrometallurgical treatment (Tirronen et al., 2017) and end up into the cast anodes. During the electrorefining stage, metals more noble than copper such as gold and platinum, are not dissolved but enrich into the anode slimes. In contrast, silver may dissolve slightly and thus, minor chloride addition is used to retain silver in the slime as sparingly soluble AgCl. Moreover, other metals less noble than copper may also dissolve, such as nickel. Therefore the electrolytes used in electrorefining typically contain substantial amounts of copper, nickel and even arsenic as well as minor metals such as antimony and bismuth. In the Boliden electrorefinery these were reported to be in the magnitude of 51.2– 60.4 g/L of Cu, 10.9–15.8 g/L Ni, 7.2–15.9 As, 0.2–0.4 Sb and 0.1–0.4 Bi with an associated sulfuric acid concentration of 139–155 g/L (Lehtiniemi et al., 2018). Copper is the most noble of the dominating base metals in the electrolyte and is thus deposited on the cathode as 99.99% purity LME-A grade. Anode slimes are collected and subjected to precious metals treatment e.g. via pressure leaching—selenium recovery— Doré smelting—Ag refining—Au/Pt/Pd leaching and reduction process (Ludvigsson & Larsson, 2003). The Pori refinery, operating in Finland since 1941, not only produces 133 000 t Cu cathode and 2300 t nickel sulphate annually but also 66 t silver, 4.6 t gold and palladium and platinum (in year 2017).

Jan 1, 2019

By James Kear, Romain Prioul, Robert G. Jeffrey, Andrew P. Bunger, Dimitry Chuprakov

"Unconventional gas and geothermal reservoirs are typically naturally fractured and therefore the challenging problem of hydraulic fracture (HF) growth through naturally fractured rocks is an important issue especially for the development of accurate predictive HF models. This paper presents results from laboratory experiments in which HFs have been created in both sandstone and crystalline (gabbronorite) rock specimens such that they impinge either orthogonally or at an oblique angle on an unbonded, machined frictional interface. Depending on the conditions of each experiment, the fractures either cross or are blunted at the interface. The growth behavior was ascertained for these experiments based on a synthesis of the injection pressure record, active ultrasound monitoring, and direct post-experiment inspection of fractured specimens. From these experiments we observe: 1) A contrast between direct crossing and crossing with an offset for orthogonal and oblique intersection, respectively, 2) Apparent independence of crossing/blunting behavior on the friction coefficient for orthogonal intersection, 3) Dependence of the stresses required to promote crossing on the intersection angle between the HF and NF, 4) Existence of cases in which the hydraulic fracture crosses but then essentially ceases propagation such that all fluid is diverted to the interface. INTRODUCTIONHydraulic fracturing is a vital technology used to increase the productivity of oil, gas, and geothermal wells. Predicting hydraulic fracture (HF) growth is, in turn, critical to design of hydraulic fractures that grow to the desired length, accept the desired amount of proppant, and remain contained in the reservoir without unwanted height growth into surrounding layers (e.g. Economides and Nolte, 2000). The importance of HF modeling has prompted 6 decades of research during which simulators have become more efficient, more accurate, and have addressed a growing range of complexities (see review of e.g. Adachi et al., 2007).One of these complexities is the interaction between HFs and mechanical discontinuities such as natural fractures (NFs). Efforts in this area have been mainly driven by development of unconventional (i.e. low permeability) oil and gas resources because essentially all viable low permeability reservoirs, including shale gas/oil reservoirs, are naturally fractured to some degree (King, 2010). One of the most important questions for developing effective HF stimulation strategies in these reservoirs is whether the hydraulic fracture(s) is/are expected to be single-stranded or whether interaction with the NFs will lead to network-like growth. The basic building block for numerical simulators that can address this question (such as Kresse et al., 2013 and Weng et al., 2014) is whether an HF that intersects an NF will cross the NF or whether its growth will be captured by the NF so that additional fluid injection pressurizes the NF but does not generate ongoing growth of a new HF. These scenarios, including subcategories such as crossing with an offset, have been recognized for several decades (Daneshy, 1974; Warpinski and Teufel, 1987, and as recently reviewed and expanded by Chuprakov et al., 2013)."

Jan 1, 2015

By Zara Hosseini

?Microseismicity ?Seismic Systems ?Intrinsically Safe and Explosion Proof Seismic System ?Case studies: ?Gas Drainage Optimization ?Fault Identification ?Conclusion Seismic Event ?Occurrences in which energy is released in the rockmass creating a series of seismic waves propagating throughout the rockmass ?Can cause a Fall of Ground or CoalBurst Factors creating Seismicity: ?Mining at Depth ?High stress zones ?Major geological structures ?Mining practices and strategies ?Mining activities i.e. drilling and blasting

Aug 1, 2013

By F. E. Goodwin

Since the last CIM Zinc and Lead Conference ten years ago, significant technical and market forces have influenced how these metals are used, and the geographic distribution of their uses. Unprecedented price fluctuations have opened competitiveness issues, while the rapid growth of the Chinese market has created challenges both inside and outside China. Recent technical developments in battery energy storage, coatings, castings and chemical applications of lead and zinc will be reviewed together with the influence of these trends on end use markets.

Jan 1, 2008

By M. Uszko

The climatic area in which Poland is located requires heating the ventilation air at intake shafts during the winter season. Air heating of the intake shaft should ensure safe operation of hoisting devices; while at the same time it also affects the conditions of the mine environment. The paper presents the issues of shaft heating in coal mines in terms of the mining law, the effect on the conditions of the mine environment and heating technology solutions used in the mines of Kompania Weglowa S.A. (KWSA).

Aug 1, 2013

By Ahmad Ghahreman, Denver Cowan, Yeonuk Choi

"Testwork was conducted in order to compare the effectiveness of carbon based catalysts while oxidizing a gold-bearing pyrite concentrate under atmospheric conditions. Without the use of a catalyst the oxidation of pyrite was incomplete after 96 hours, resulting in roughly 60% pyrite oxidation. Furthermore the resulting sulphate yield from unassisted pyrite oxidation ranged between 72 and 84%. It is evident that atmospheric oxidation of pyrite is not viable due to slow oxidation kinetics and high sulphuric acid production when using a ferric sulphate media without a catalyst. The effect of two different carbon based catalysts, one Lewatit® AF 5 a new microporous carbonaceous bead, and the second a granular coconut shell based activated carbon, were tested under the same oxidation conditions as the unassisted pyrite tests. After 96 hours, Lewatit® AF 5 assisted oxidation showed approximately 96% pyrite oxidation with a sulphate yield ranging between 26 and 35%, while the activated carbon assisted oxidation reached approximately 100% pyrite oxidation with a sulphate yield between 36 and 37%. Testwork indicated that not only does the addition of a carbon based catalyst greatly improve the oxidation kinetics and lead to almost complete oxidation, the sulphate yield is also drastically reduced, resulting in very high elemental sulphur yields.INTRODUCTION Pyrite is an important sulphide mineral due to its ability to contain invisible gold concentrations up to 132 g/t (Chryssoulis & Cabri, 1990). As a result, ores composed of only a small amount of pyrite still have the ability to contain high gold grades. This refractory gold cannot be accessed via conventional gold leaching processes, such as cyanidation, and additional oxidative pre-treatment is required to liberate the gold, making it more amenable to extraction (Marsden & House, 2006). Current oxidative pre-treatments do exist consisting of both pyrometallurgical and hydrometallurgical processes including high temperature and high pressure leaching within autoclaves, biological atmospheric leaching and roasting. Autoclaves are a proven process reaching desirable recoveries within approximately a 1–2 hour retention time, due to the increased temperatures and pressures, allowing for an increase in dissolved oxygen (Marsden & House, 2006). The typical reaction for pyrite oxidation within autoclaves is presented in Equations 1, 2 and 3."

Jan 1, 2017

By Ausenco Engineering Canada

"This paper demonstrates the selection of grinding circuit technology for a number of recent projects including discussion of the key drivers and the role of energy efficiency. Decreasing head grades combined with a strong and sustained increase in operating costs has forced miners to examine increased project size, increased equipment capacity and efficiency improvements in order to reduce their unit operating costs and improve overall project economics. Comminution energy consumption, safety and capital cost considerations play a critical role in the success of projects. This paper presents some key guidelines for a successful and cost effective comminution circuit design and includes a case study on three projects, outlining the issues and the drivers which led to the ultimate circuit selection and the critical role that energy efficiency played.INTRODUCTIONComminution circuits for minerals processing are selected based on their suitability and efficiency in reducing run-of-mine ore to the desired feed size for the downstream process. The input material (ore) properties and downstream process requirements are the key determinants and there are standard approaches for each circumstance.The minerals processing industry has been a fast adaptor of efficiency improvements based on increasing capacity of equipment (e.g. trucks, crushers, mills, pumps) but less successful in adapting radically new technologies that disrupt incumbent flowsheets or processes.The installed power of grinding mills has increased linearly over the past 25 years (Meka & Lane, 2010) and pumps and classification equipment have kept pace. The autogenous grinding (AG) and semiautogenous grinding (SAG) mills displaced stage crushing as a dominant method of coarse rock breakage in many applications causing crusher manufactures to increase the capacity of cone crushers to meet the competitive demand.Examples of new comminution technology in the 20th and 21st centuries are the development and adoption of cyclone classification in the 1940s (Newtech, 2016), AG milling in the late 1950s, vertical grinding mills in the 1980s, high pressure grinding rolls (HPGRs) also in the 1980s and ultrafine milling technology in the 1990s (Meka & Lane, 2010)."

Jan 1, 2016

By Ross Gallinger

In 1997 a group of Canadian mining companies met to review the Mine Environment Neutral Drainage (MEND) program and to consider future activities. They concluded (i) that Canadian industry and NRCan should fund a small secretariat in Ottawa to support technology transfer in Canada and (ii) that it was important for industry to continue the momentum of MEND on an international scale. The need for INAP (International Network for Acid Prevention) was strongly endorsed by company, university, consultant and government experts from Australia, Canada and the U.S. who were convened in Vancouver in February 1998. The initial focus was the development of a solid knowledge base covering the collective experience of INAP's members to promote the dissemination of successful practices, the identification of knowledge gaps and the formulation of effective research proposals. The sharing of information on past successes and failures alone was viewed as sufficient justification for the formation of INAP. INAP was officially launched in October 1998, and is now an effective, industry based initiative to globally coordinate research and development in the management of sulfide mine waste. Significant improvements in the management of sulfidic mine materials through knowledge sharing, research and development of technology by INAP will reduce liability associated with acid drainage. This paper will explore the international efforts and activities of INAP.

May 1, 2002