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By Stephen L. Chryssoulis, Stamen Dimov

"Preg-robbing has been known for many years, where increased losses are suffered because dissolved gold is removed from solution by adsorption onto carbonaceous matter. In direct cyanidation circuits it is reasonable to conclude that the preg-robbed gold is either in a gold cyanide [Au(CN) - 2, AuCN] or metallic [Au°] form. However, in circuits with a pre-oxidation step possibilities increase and multiply even further because of water recycle streams containing apparent and not-so-apparent gold ligands. It is in these circuits where speciation of sorbed gold, i.e. the identification of the gold compound, is useful. The importance arises from the fact that proper identification of the sorbed gold species can be used to determine how, when, where and why gold was removed from solution, thereby identifying the exact cause of the problem and providing clues as to how it may be rectified.INTRODUCTIONTo the best of our knowledge, this is the first attempt ever to speciate gold preg-robbed by carbonaceous matter using a surface sensitive microbeam technique. This approach enables the direct determination of gold species sorbed on carbonaceous particulates, opening an entirely new field in the understanding of the chemistry of gold sorption on carbon. The reasoning behind this effort was to add to the current knowledge of the detrimental effect chloride ions have on gold recovery by the pressure oxidation and in particular why in the ensuing CIL step, gold is not being desorbed from the surface of the carbonaceous particles (Table 1)."

Jan 1, 2004

By C. A. Horne

"The transportation of mineral solids in the form of slurry is a subject most of us are associated with and, in fact, live with on a daily basis. The design parameters of slurry systems and most important the prime movers or cent¬rifugal pumps, are frequent and often controversial subjects due to the lack of practical guidelines which, if known and followed, can increase both reli¬ability and service life of the equipment.In this talk, emphasis has been placed on the practical side or rule-of-thumb approach to applications which, in turn, has been related to successful field results. The theoretical content and complex design criteria associated with actual equipment design has consequently been held to a minimum in the following discussions.I. BASIC SLURRY PUMP DESIGN CONSIDERATIONSFirst, to better understand how a centrifugal pump performs work, a basic description of the operating principles are in order.A. Operation In a pump, mechanical energy is transformed into pressure energyby virtue of the centrifugal force exerted by the rotating impeller. The liquid is discharged by centrifugal force at a velocity required to generate a given head and the volute collects the liquid so useful work can be done by the conversion of kinetic energy to pressure energy."

Jan 1, 1976

By Bryn Harris, Liming Huang, Andre Laplante

"This paper reviews flowsheets generally used in gold rooms to upgrade primary gravity concentrates particularly those of Knelsons. It is concluded that even for small operations, which treat between 250 and lo00 kg of concentrates per day, there is a strong economic incentive to include in the flowsheet magnetic removal of tramp iron, at least two shaking tables, screening of either table feed or table tails at 150-212 um, and scavenging of table tails with a small centrifuge. Headroom, rather than floor space, is often inadequate in most gold room designs, and limits gravity flow and flowsheet flexibility. Experimental data are presented to demonstrate the effectiveness of a small Knelson Concentrator to scavenge significant amounts of gold (up to 91 %) from fine table tails.RésuméCet article examine les schémas d’évolution généralement utilisés pour traiter les concentres gravimétriques d‘or, en particulier ceux produits par concentrateur Knelson. Nous en venons à la conclusion que même pour un petit circuit d’une capacité de 250 A 1000 kg/jour pourrait bénéficier des opérations unitaires suivantes : concentrateur magnétique pour extraire la feraille, au moins deux tables A secousses, criblage de l’alimentation ou du rejet d’une ou des tables i une maille de 150-212 um, et épuisages des rejets fins de table avec un centrifuge de petite capacité. C’est l’espace vertical du lieu où se fait cette concentration qui représente la contrainte la plus importante, plutôt que sa surface, puisqu’il faut maximiser l’écoulement par gravite des pulpes et s’offrir une certaine flexibilité quant à l’agencement final des opérations unitaires. Nous présentons également des données expérimentales pour démontrer l’efficacit6 d‘un Knelson de laboratoire pour récupérer jusqu’ à 91 % de l’or contenu dans les rejets fins de table."

Jan 1, 1999

By George W. Bain

Summary During the last three years the discovery of gold in the belt of volcanic and sedimentary rocks extending eastward from the Porcupine and Kirkland Lake gold-fields has caused a great deal of excitement in mining circles. The area is heavily drift covered, and every aid to the location of veins is eagerly grasped. A knowledge of the physiographic history of the area is of the utmost importance in the application of many of these aids. Evidence is presented to show that glacial erosion has lowered the general elevation very little below the pre-glacial level, and that many glacial erratics have been carried less than three miles southward. Probably a knowledge of the general geology of a: region was never more necessary to the understanding of the distribution and continuation in depth of the mineral veins than in this area. Four distinct granites occur in the region, and gold-bearing veins are genetically associated with only one of these. Two types of quartz-feldspar porphyries have been found, only one of which has any bearing on the locus of the mineral veins. Many other examples of this complexity of associations might be cited, but everyone goes to show that in most cases the economic importance of the deposits can be realized only after the regional geology is understood. A series of sandstone, limestone and shale intruded by granite lies unconformably below the Keewatin lavas. The latter are intruded by a gneissoid granite and are overlain unconformably by the thick series of Timiskaming greywackes and silts. These are intruded by carbonated syenites and syenite porphyries which have since been rendered somewhat schistose.

Jan 1, 1927

By Yasser Mohamed

Daily field management of earthmoving operations requires quick and regular decisions for allocating available equipment to different jobs on a project. A general foreman?s day starts with matching several activities with a suitable set of available equipment to achieve the highest productivity and lowest unit cost. Usually, this decision-making process needs to be quick, and depends to a great extent on the foreman?s experience, which varies from one individual to another. Many analytical solutions with various degrees of sophistication and optimization exist to address such decisions. However, adopting any of these solutions is contingent on how accessible and easy-to-use the solution is. This paper discusses the development process of a webaccessible solution for evaluating earthmoving fleet composition and allocation scenarios. The solution relies on discrete event simulation and an optimization backend engine, but introduces the user with a simplified and easy-to-use interface that is accessible from any mobile device, and is customized to specific user?s needs. The developed system gathers most equipment and site-related input data from a company?s information systems to minimize user input. The user mainly needs to formulate equipment and job combinations and allocation scenarios (e.g. soil type, quantity, and hauling distance), according to equipment availability each day. Then the system will evaluate the productivity and unit cost estimates for each scenario, allowing the user to choose the most suitable one. It may also be used to automatically recommend the optimum solution given an available list of equipment. The paper presents the process followed in prototyping the proposed system in collaboration with a major Canadian earthmoving contractor, and customizing it to the user needs within the company. It also describes the overall structure of the developed system and its core simulation model.

Aug 1, 2013

By J. E. Nesset, F. Rosenblum, J. A. Finch

"The self-heating of sulphides can be a major hazard in mining operations and concentrate handling, particularly during transportation and associated storage. Self-heating results from the oxidation of sulphide minerals and can vary from being insignificant to highly reactive and potentially hazardous to both humans and infrastructure. It is essential that there be a reliable test methodology that can measure and categorize a given sulphide material as to its self-heating potential. By their nature, sulphide ores and concentrates are complex and variable mineral mixtures making it difficult to predict their self-heating behaviour a-priori based on mineralogy or with a simple “snapshot” test. Furthermore, self-heating behaviour will depend on the state of oxidation of the sulphides as well as time, temperature and humidity. A review of available testing apparatuses and protocols that can be used to assess self-heating potential is presented. Each of these methodologies was examined in relation to its ability to measure and reliably predict the latent self-heating hazard of a sulphide material. Several of the methods were tested and compared to illustrate their strengths and weakness. The results indicated that a number of the test protocols may produce false negative indications of self-heating potential, constituting an obvious concern to the industry.INTRODUCTION Sulphides as well as other materials (coal, wood chips, hay, powdered milk, to name a few) that are stockpiled in an air atmosphere may undergo oxidation reactions which can result in the evolution of heat (Beever, 1984) (Hudak, 2002) (Blanchard, 2007). If the rate of heat generated exceeds the rate of heat dissipation, the stockpile temperature will rise, potentially leading to “hot spots” in the most reactive areas, and possibly even fires. The heat generation rate, the “self-heating” rate, depends on many factors such as the type and composition of material, particle size, moisture content, oxygen availability, ambient temperature and humidity, and of prime importance, the extend of prior oxidation, or more specifically, the presence of oxidation products. The desire of operators that mine, process or transport sulphide-bearing materials with a potential for self-heating is to have an accepted and reliable method for evaluating and quantifying the potential hazard of their material. The challenges are how to best measure the self-heating properties of given samples, and based on results, predict the behaviour of the bulk material over time and in-situ. Generally, when evaluating a given material one derives the self-heating characteristics of that sample at the time and under the conditions of testing, which will be referred to as a “snapshot test”. If that material is invariable, i.e. it will not change its response over time, then it may be considered to be a “predictive test”. However, if as a result of continuing oxidation or other changes, the material becomes more or less reactive with time, then a “snapshot test” is unreliable with respect to predictive ability."

Jan 1, 2014

By Murray Wood, Michael Schaffer, Makat Katom

"An expert system applied to the control of mineral process unit operations is, by its nature, the site best operating practice, having been designed by the local experts in conjunction with consulting metallurgists. The “common sense” layer in a MET (MinnovEX Expert Technology) solution determines an appropriate action for the current operating conditions through a developed heuristic model of the process (expert system). The magnitude of the setpoint change that is made is proportional to the confidence that the system has in its interpretation of the current conditions (fuzzy logic). The solution is always striving to take the process to a constraint and thereby optimise the operation. An accepted limitation of the solution is that the only way the system can determine if a constraint has been reached is to exceed it and then withdraw – essentially “experimenting” with the process. By leveraging a model, which can accurately ""simulate"" the process, this restriction can be circumvented by pre-testing the set point change through a ""what if"" analysis and then modifying the solution as appropriate.At Ok Tedi, the introduction in 1999 of a MET expert system for SAG milling resulted in significant improvement in circuit throughput. Yet, with the additional inclusion of an accurate model of the process there was still more that could be achieved. Hence, in 2002 a MET Neural Network model was developed and deployed to enhance the existing expert system solution. The principal objective of this model was predicting the effect that changes in SAG tonnage and density would have on the power draw of the mill - essentially a power predictor. The results have seen a decrease in process variance with an associated increase in average circuit performance.This paper describes the methodology by which the Neural Network model was implemented, the considerations and limitations when applying this technology and ultimately the results that were achieved."

Jan 1, 2003

"Here, we statistically proved that giant earthquakes occur at lunar phases specific to each subduction zone. Enough attention during the lunar period, especially when seismicity is occurring, will significantly reduce damage from giant earthquakes. Two case studies in which giant earthquakes occurred after seismicity in dangerous lunar phases were discussed, and the mechanisms underlying why giant earthquakes occur around neap tide at some subduction zones were explained by prohibition of giant earthquake occurrences due to high strain rates at spring tides at N–S subduction zones. The prohibition was statistically proven for uniaxial creep tests on Inada granite with slight stress disturbances. INTRODUCTIONIn previous studies, we showed that from 1900 to present, giant earthquakes (MW ??8) have occurred at lunar phases specific to each subduction zone (Fujii & Ozaki, 2012; Ozaki & Fujii, 2012). Although we later proposed a possible reason for these occurrences, the study lacked statistical analyses (Fujii et al., 2013). Therefore, this paper shows the results of such statistical testing and presents case studies for the Tohoku 2011 and Chile 2014 events, thereby providing updated data on giant earthquakes through July 2014."

Jan 1, 2015

Les Mines Inmet ? La Division Troilus exploite une mine d?or à ciel ouvert depuis 1996 et produit un concentré de cuivre. La Division Troilus est localisée à 175 KM au nord de la ville de Chibougamau? au 51 parallèle.

Feb 1, 2008

By C. Rodgers, E. (Ted) Warren

"LocationThe Key Lake operation of Cameco Corporation is located at latitude 57°N in northern Saskatchewan, within the southem boundary of the Athabasca formation. The nearest city is LaRonge, located 240 km to the south. Access to the mine is by all-weather road and by private airstrip.Description of OperationThe mill was designed to produce twelve million pounds of uranium oxide (U3O8) a year from a feed grade of 2.4% U3O8. Current production is fourteen million pounds from 2.0% feed.Following grinding, the uranium is leached using sulphuric acid and oxygen in autoclaves. An eight thickener counter current decantation (CCD) circuit is used to separate the uranium-bearing solution from the solid waste residue. The uranium in solution is further purified in a solvent extraction circuit. The purified uranium is then precipitated using ammonia, calcined at 840°C, and packaged in drums for shipping to refineries. There is a crystallization circuit to recover excess ammonium sulphate produced in the process, and a waste treatment circuit.HistoryUranerz Exploration and Mining discovered the Gaertner and Deilmann orebodies in 1975 and 1976, respectively. Between 1975 and 1977, Uranerz conducted laboratory studies and delineated a process for the Key Lake ore known as the ""Bonn process."" In 1977, Sherritt Gordon Mines Ltd. was retained to conduct further studies in cooperation with U ranerz. The technical feasibility of the Bonn process was generally confirmed. Howeve1~ alternative processing methods also appeared feasible, and over the period 1978-1979, a detailed research and development program was conducted to finalize the processes to be used and to provide data for design of the plant."

Jan 1, 2000

By Jessica Barber

Problem ? Mining operations consistently need equipment that is available, and able to perform to its maximum potential ? The most difficult part of a Maintenance Manager?s job is often a lack of knowledge on how long their equipment has to last ? The short term view can lead to interim fixes that accumulate into larger problems ? It is always difficult to justify major overhauls and upgrades when there is pressure to meet mine plan production targets

May 1, 2008

By A. Deneys

This paper reviews industrial gases used in primary copper production. Copper smelting industrial gas demand has steadily increased since the first commercial oxygenconcentrate smelting in 1952 [1]. In copper production oxygen for smelting is the dominant industrial gas use followed by oxygen for converting. Nitrogen is finding increased use in copper smelters. Nitrogen is used for porous plugs for copper converting and anode refining [2-5]. Nitrogen can be used for concentrate drying [6,7] and is also used in some Ni-Cu smelters as a coolant in Peirce-Smith converting [8,9]. Industrial gas supply options of cryogenic or adsorbent based on-site plant or cryogenic liquid delivery are detailed.

Jan 1, 2007

By Olaf Kessler, Jan Kalich, Michael Reich, Julia Osten, Uwe Füssel

Modern automobile bodies consist of different materials, e.g. aluminium alloys and high strength steels. Mechanical joining, e.g. clinching, is very suitable for joining aluminium and steel sheet. But clinching needs a sufficient ductility, which is no longer supplied by high strength steels. Laser-assisted clinching has been shown, to be able to join aluminium and high strength steel sheet successfully. Thereby the steel sheets were heated locally for short times to increase their ductility. Due to the thermal contact between steel and aluminium sheet the aluminium alloys also achieve a local short-time heat treatment. This fact may cause a significant impact, as aluminium sheet in automobile bodies is often used in T4 (or similar) condition and later artificially aged during the paint bake cycle. Aluminium alloys 6016 and 6181 have been short-time heat treated with heating rates up to some 100 K/s. Precipitation and dissolution processes have been monitored in-situ by calorimetry. Mechanical properties have been investigated on as well as after short-time heat treatment by deformation dilatometry. The results show, that suitable short-time annealing parameters during laser-assisted clinching can increase ductility and at the same time act as retrogression for aluminium sheets, resulting in increased strength after aging.

Jan 1, 2015

ABSTRACT Understanding process histories and worker exposures in nickel production operations is critical in determining the role nickel compounds play in respiratory cancer incidence. As part of a series on Vale Canada’s (previously known as Inco) nickel processing operations, this paper includes descriptions of Ni electrolytic operations at refineries in Port Colborne, Ontario (1922–1984), and Thompson, Manitoba (1961–present). Industrial hygiene measurements, by area and personal sampling, of workplace aerosols at these operations are reported.

Jan 1, 2014

By D. B. Felsher

"Lakeshore Gold’s Bell Creek Mill is located in Timmins, Ontario. The mill has been in operation since 2009 and has undergone several small expansions since then. In 2012 - 2013 the first major mill expansion was commissioned raising the mill capacity from 2,000tpd to 3,150tpd. This was done through the installation of a new ROM ore truck dumping facility, jaw crusher, ore storage dome, SAG mill, leach tank, CIL tank, and electrowinning cell. This paper will cover the equipment installed to raise the tonnage as well as the commissioning of the new equipment including problems encountered and how these problems were solved.IntroductionLake Shore Gold acquired the Bell Creek Mill, along with the Bell Creek Mine, from the Porcupine Gold Mines Joint Venture, a joint venture between Goldcorp Canada Ltd. and Kinross Gold Corporation, in December 2007.The Bell Creek mill, which processed ore from the Bell Creek Mine has consistently achieved recoveries of over 95%, is a conventional gold mill circuit, involving crushing and two stage ball mill grinding, gravity and leaching, followed by Carbon-In-Pulp (CIP) process for gold recovery. The facility had been placed on care and maintenance in 2002. At the beginning of 2009, the mill had been refurbished with an initial capacity of 800 tonnes per day and was subsequently refurbished to a capacity of 1,500 tonnes per day near the end of the third quarter of that year. The Mill was then expanded in 2010 to a capacity of 2,000 tonnes per day.In late 2011, the Company commenced a 50% expansion of its milling facility, from a processing capacity of 2,000 tonnes per day to 3,150 tonnes per day. Phase 1 of the expansion, which mainly involved enhancements to the solution circuit (“back end”) and increased the mill’s capacity to 2,500 tonnes per day, was completed at the end of 2012. Commissioning of Phase 2 of the expansion, to a capacity of 3,150 tonnes per day, commenced at the end of July 2013."

Jan 1, 2015

By G. Azimi, K. K. Varanasi1, A. T. Paxson, R. Dhiman, H. -M. Kwon

Hydrophobic materials that are robust to harsh environments are needed in a broad range of applications. Although durable materials such as metals and ceramics, which are generally hydrophilic, can be rendered hydrophobic by polymeric modifiers, these materials deteriorate in harsh environments. Here it is shown that a class of ceramics comprising the entire lanthanide oxide series, ranging from ceria to lutecia, is intrinsically hydrophobic. Their hydrophobicity is attributed to their unique electronic structure, which inhibits hydrogen bonding with interfacial water molecules. In addition, this work demonstrates that these ceramics sustain hydrophobicity even after exposure to high-temperature environment (1000 °C for 2 h in air). It is envisioned that this class of robust hydrophobic materials will have far-reaching technological potential in various industrial applications, where water repellency and dropwise condensation are desirable.

Jan 1, 2014

By Michel Rodrigue, Sylvain Duchesne, Louis Racine

"LocationThe Louvicourt mine is located 20 km east of Val d'Or in Abitibi, in the northwest part of the province of Quebec. The mine is located on Highway 117 connecting Val d'Or to Montreal and very close to the main railway networkHistoryFive successive exploration attempts by Aur Resources resulted in the discovery of the large Louvicourt orebody in June 1989. Construction of the surface and underground infrastructures commenced in the spring of 1991. Milling operations commenced in July 1994. The entire project cost CDN$290 million, almost CDN$20 million less than initially estimated. The concentrator infrastructure cost CDN$64 million.Louvicourt mine is owned in partnership by Novicourt Inc. (45%), Teck Corporation (25%), and Aur Resources Inc., the administrator (30%).Brief DescriptionLouvicourt mine is the largest producer of base metals (Cu and Zn) in Abitibi-Temiscamingue. Its average daily production is nearly 4300 t of ore, for an annual production of 200 000 t of copper concentrate (28% Cu) and 33 000 t of zinc concentrate (57% Zn). After only a few weeks of operation, it had attained its objectives for the most part, and operations continue to be improved."

Jan 1, 2000

By G. R. Peeling

The Mining Association of Canada launched the Towards Sustainable Mining initiative in 2004. TSM's goal is to improve the mining industry's performance by aligning its actions with the priorities and values of Canadians. The initiative currently includes performance indicators for four areas: tailings management, energy use and greenhouse gas management, external outreach and corporate crisis management planning. Over the past year, the association has been designing a performance assessment and verification system for these performance areas, as its members prepare to move external verification of their performance in 2007. The initiative and its evolution, as well as the challenges faced in developing a verification system applicable to an entire sector will be examined.

Jan 1, 2007

By K. A. Clark

"The repacked mineral aggregates of good grade oil sands have permeabilities ranging between 15 darcys to 350 millidarcys. The variation is due to the silt contents of the aggregates. Few good grade oil sands contain as much as 30 per cent •silt, most of them contain less than 20 per cent, and a large proportion have less than 10 per cent.The permeabilities of repacked good grade oil sands (oil included) depend on the degree of liquid saturation. When saturation with oil plus water reaches between 80-90 per cent, permeability is reduced to zero. As total saturation decreases below 80 per cent, permeability increases ranidly. Permeabilities of between one and two darcys were observed for total saturations between 60-70 per cent.The mean value for 18 measurements of the permeabilities of ""undisturbed"" core samples of good grade oil sands was 50 millidarcys. This value is •probably too high. The mean value for 20 measurements on core samples of interbedded oil sand and shale was 100 millidarcys. The mean value for 11 measurements on shale was 10 millidarcys."

Jan 1, 1960

By T. A. Grammatikopoulos, B. Vasily, A. H. Clark

"The St. Lawrence deposit is a large wollastonite skarn (ca. 9 Mt @ 41.3% wollastonite) adjoining the gabbroic-to-syenitic Leo Lake pluton in the granulite facies Frontenac Terrane of the Grenvillian Central Metasedimentary Belt. It occurs within a horseshoeshaped horizon of quartzite, open to the east. The skarn extends over 1.2 km2, and comprises wollastonite-dominant, wollastonite-clinopyroxene, and diverse quartz-feldspar-sulphide (-titanite) layers, interbanded with, and strongly folded within, the quartzite. As in the world-class wollastonite deposits of the Willsboro district, New York, no carbonate protolith is preserved, and calcite is a negligible constituent of the mineralized zones. Wollastonite development is nonetheless ascribed to metasomatism of a metacarbonate unit by magmatogene, silica-rich, CO2-poor (XCO2 < 0.05) fluids, at P = 350 MPa and ca. 560°C, or, alternatively, 550 MPa and ca. 630°C.Several high-grade zones, averaging >40% but locally exceeding 80%, of translucent, white, tabular wollastonite grains, with lengths of 0.2 cm to 5 cm, have been delimited by drilling. Preliminary beneficiation studies yield high aspect-ratio and high-purity (low Fe and Mn) concentrates.St. Lawrence compares favourably to other known prospects and operating wollastonite deposits: having good chemical and physical properties, low iron content, and high aspect ratios (>20:1). In addition, the deposit has a favourable size and location, and will benefit from a low Canadian dollar. Canada currently has no wollastonite production."

Jan 1, 2003