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By L. A. M. Castro

As Canadian mines progress to greater depths, magnitudes of induced stresses increase, becoming high enough to cause rock mass damage and failure during excavation. In addition, depending on the orientation of key geological structures in relation to the in-situ stresses, induced shear loading can be developed on these structures, creating the potential for: a) remobilization of existing geological structures, b) formation of new seismically active structural zones, created through rock mass damage and coalescence along such structural zones, and/or c) interaction between existing and newly created structures. Numerical analyses were carried out to investigate four possible factors that might cause fault slip on controlling structures, namely: (a) unclamping, (b) day-lighting, (c) stress rotation and (d) pillar shear. Application to an underground mine in the Sudbury Basin allowed verification of these factors and the proposal of two alternative mine planning methods to limit fault slip on key structures: (1) pillar clamping and (2) stope sequencing.

May 1, 2009

By Steve Piercey

Introduction ? VMS Deposits: The Target ? Key points for every belt: heat flow and extension. ? Good felsic rocks ? Good mafic rocks. ? Petrochemical assemblages. ? Summary Key Points Throughout ? Common themes: ? Heat ? driver of the hydrothermal system ? Extensional geodynamic setting ? conduits to focus fluid flux ? (e.g., Lesher et al., 1986; Swinden et al., 1991; Barrie et al., 1993; Lentz, 1998; Syme et al., 1999; Piercey et al., 2001, etc.) ? We must identify rocks, belts and tectonic environments that encompass these two criteria (among others but?) ? e.g., forearc rifts, intracontinental rifts, arc rifts, and back-arc basins.

Apr 1, 2005

By Jose A. Jimenez

"Mining operations generate an enormous amount of data that is difficult to organize, analyze and act on. These data require an extremely broad range of experts to investigate and manage the cross-disciplinary information. The data collects in paper files, diverse databases, historians, stand-alone applications, and excel files. This collection of sources represents everything from monthly, weekly, or daily inputs to real-time feeds or sporadic unscheduled entries. With the operational complexities ever increasing and fewer engineers per mine, an efficient operation is becoming more and more challenging. Engineers are typically burdened with data collection, clean up, and administrative efforts leaving very limited time for engineering assessment and/or optimization analysis. Often optimization becomes limited to the analysis of equipment uptime through existing field automation systems. A great portion of the field data is tucked away in historians seldom reaching those engineers who might leverage the data. Few mine operators have the time or budget to re-architect their operations data collection or management practice, so solutions must enable improvements without requiring expensive or time-consuming implementation. This presentation highlights examples where the aforementioned challenges are addressed using a solution framework designed to enable: 1) data integration and connectivity, 2) monitoring and opportunity recognition, and 3) engineering workflow automation. The initiative extends the concepts and success proven in the automation market segment to all disciplines across the mine operations. INTRODUCTIONThe mining industry by its very nature spends a great deal of its capital on equipment maintenance and replacement. In addition, periodic shutdowns due to equipment failure are typically very costly in terms of interrupted operations. Keeping mining equipment running at peak performance and avoiding costly shutdowns can make a huge difference in the overall return from mining operations. Today, information can be make available that can go a long way towards spotting equipment issues and permitting timely intervention to avoid costly unplanned shutdowns. That said, gathering all of the information from numerous points on many different pieces of equipment necessary to enhance overall equipment effectiveness presents its own daunting issues."

Jan 1, 2016

By Rene Klymowsky, Norbert Patzelt, Egbert Burchardt, Johann Knecht

"The challenge of ""ore bodies getting steadily harder and lower in grade"" was brought to light during the first oil crisis in the 70's. Shortly afterwards, HPGRs appeared on the scene with the promise of saving energy. This combined with developments in wear protection for the rolls ushered in a period of trade-off studies that considered the HPGR as an option to improve project economics or to even make projects feasible at all.Since then, applications of HPGRs at Cerro Verde (Freeport), PTFI Grasberg (Freeport), Mogalakwena (Anglo Platinum), Tarkwa (Goldfields), Boddington (Newmont), Penasquito (Goldcorp), and others have contributed to the creation of a formidable basket of operating experience. Collected through years of successful operation, this information has been used to validate design criteria, scale-up factors and establishing a clearer picture of what ""to do"" and what ""not to do"".This paper compares results from various mining operations using HPGRs in their processing plants. Some of the lessons learnt in different operating environments are reviewed in order to support proper implementation and operation of HPGR's. Some of the development programs that have been initiated to improve wear life of the tyres and to reduce overall operating costs are reviewed. It is timely to summarize today’s experience and analyse its implications for existing and new operations"

Jan 1, 2012

By T. Yameogo

Many ideas, tools, technologies, and methodologies are believed to have staked their claims on the future of mining. For example, automation is strongly positioned as the platform within which mining will be practiced. A subset of automation ? intelligent mining ? will add some smart interactions between machines, technologies, the rock, and the environment. The future also calls for an improved approach to sustainability and corporate social responsibility. Mines of the future are dreamed of to be more ethical and more balanced. They will boast optimized designs, integrated value and supply chains, produce less waste, recycle and reuse, and will require less energy to operate. Then, what about the people that will operate this optimized ecosystem? How is the education system teaching the operators of the mines of the future? What kind of a future should mining education foresee to prepare the workers appropriately? In recent years, the shortage of skilled labor for mines around the world has created a tough competition to attract, retain, and train the very people without whom mining will cease to exist. In Australia, Canada, and the United States in particular, the war for talent has resulted in higher-than-usual labour costs. Such costs have dented the unit costs of many mining businesses. Concomitantly, mining contractors? and consultants? prices have increased to reflect the escalation of labour costs across the value chain. From labourers to engineers, from juniors to seasoned professionals, the increase in compensation is unprecedented. Yet, the shortage is still hurting the industry, and the high calibre candidates continue to be rare gems. The industry has been implementing aggressive solutions that include the increased hiring of skilled immigrants, the training and recruitment of minorities, and the retaining of near-retirement experienced employees. Public relation campaigns about the benefits of embracing careers in mining are also common. The CIM has also devoted a ?M4S? section to its pan-Canada meetings to educate the public, especially the youth, about the importance of the mining industry for Canada. Moreover, mining associations and universities are enticing students? enrolment through scholarships and financial support. Still, the balance between quantity and quality of workers can be discussed. This paper intends to discuss the present state of mining education as an essential part of the future of mining. The authors brush the picture of the education of miners, technicians, and engineers, against the backdrop of the technology-advanced mines of the future.

Aug 1, 2013

By B. A. Sparkes, J. H. Reeves

"The St. Lawrence Granite hosts vein-type fluorite mineralization that was mined until 1977. Recent drilling identified a significant fluorite-bearing structure hosted in adjacent meta-sedimentary country rocks. Several phases of vein fill and brecciation indicate there are three phases of fluorite mineralization, of which the later two phases are volumetrically significant. The earliest fluorite is purple and occurs along joint and fracture surfaces, in fault-breccia matrices, and as stockwork veins. The second phase comprises primarily red, yellow, blue-green, and white colours of fluorite. The latest phase is green with lesser clear fluorite. Identification of fluorite veins in the meta-sedimentary rocks opens up new areas for exploration.RÉSUMÉ Le granite St. Lawrence contient une minéralisation filonienne de fluorite, laquelle a été exploitée jusqu’en 1977. De récents forages ont permis d’identifier une structure importante contenant de la fluorite encaissée dans des roches métasédimentaires adjacentes. Les nombreuses phases de remplissage de filons et de formation de brèches indiquent qu’il y a eu trois phases de minéralisation de fluorite et les deux dernières sont importantes d’un point de vue volumétrique. La plus ancienne fluorite est mauve et se trouve le long de surfaces de joints et de fractures, dans les matrices de brèches de failles et en tant que stockwerks filoniens. La deuxième phase comprend surtout des fluorites de couleurs rouge, jaune, bleu-vert et blanc. La fluorite de la plus récente phase est verte avec des quantités moindres de fluorite claire. L’identification des filons de fluorite dans les roches métasédimentaires ouvre de nouveaux secteurs pour l’exploration."

Jan 1, 2016

By J .. R. Dalton

"Blasting in high sulphide content ores presents at least two major safety considerations: (1) compatibility of the explosives with the ore while resident in the borehole; and (2) introduction of a flame and shock producing explosive into this environment, while minimizing the risk of reactive ignition in the chemical reaction products/sulphide dust cloud resulting from the detonation. This paper will discuss only the second consideration, i.e. post detonation reactivity.The ETI (Explosives Technologies International) Technical organization, in consultation with the U.S. Bureau of Mines, reasoned that the most relevant considerations in the development of an explosive for this application are:• minimization of reactive gaseous detonation reaction products;• flame duration reduction;• flame temperature reduction;• increased explosive sensitivity;• reduced probability of ""low order"" detonation; and• maintenance of energy level as high as possible.Obviously, not all of these are totally independent properties, i.e. increased sensitivity will reduce the probability oj low order detonation as will higher energy levels. However, these considerations were examined separately as if they were independent."

Jan 1, 1994

By S. Esfahani, M. Barati, K. Danaei

"Substituting Portland cement with slag cement is one of the most economically attractive uses of slags. For this application, high cooling rates are required to form an amorphous structure. However, this is counteracted by the need to use small coolant flowrate to allow recovery of slag thermal energy as high quality heat to the coolant fluid. Therefore, a relationship between cooling rate of slag and its structure is essential to recover the heat effectively while making an amorphous slag.A modified Single Hot Thermocouple Technique (SHTT) was employed to investigate the crystallization behavior of slags by plotting their TTT (Time-Temperature, Transformation) diagrams. Seven different slag compositions containing CaO, SiO2, Al2O3, MgO were prepared at varying basicity (CaO/SiO2 =0.5-1.4).The results indicate that with increasing basicity, the TTT curves of glassy to crystalline transformation shift to the left which means higher crystallization tendency. This agrees with the fact that with the increase of basicity, the Si-O bonds are weakened, which in turn facilitates the re-ordering and crystallization of the silicate structure."

Jan 1, 2014

By Mike Anderson

The annual budget for the repair and maintenance of equipment at Syncrude Canada Ltd is in excess of 450 million dollars. Of this amount, a significant portion can be attributed to the loss of material on various pieces of equipment throughout the operation. In order to effectively battle the different wear and corrosion mechanisms that lead to material loss, it is important to understand how materials behave in the environments in which they are used. Through the work carried out at Syncrude, and work conducted with various external collaborators, significant improvements in both equipment reliability and productivity have been achieved. This paper will review some recent field trails where materials research has demonstrated the potential for significant improvements in equipment run life and reduced maintenance costs. These field trails will demonstrate the need for understanding the interaction between various damage mechanisms and the materials used in different services. The paper will also discuss current areas of focus along with future directions for further work.

May 1, 2003

By P. Condori, G. Rech, J. Winnett

"Palabora Mining Copper has a unique ore body composition which unlike other copper ore bodies has three main components in significant proportions; these are copper bearing ore, magnetite and dolerite. The high content of dolerite, a hard barren material, creates a high proportion of pebbles which normally are recycled back to the mill. This action increases the mill bearing pressure and power progressively until corrective actions are taken.A logical action to solve the pebbles generation would be to incorporate a pebble crusher. This in fact was done however two fundamental issues were encountered; the high content of magnetite and existence of a cyclone classification section. Due to the high content of magnetite, metal detectors have not been able to work efficiently to separate tramp metal which causes damage to the pebble crushers. The existence of cyclones in the circuit had a detrimental effect on the final product when the pebbles crusher was online producing coarse sandy material.Due to the difficulties in treating pebbles via conventional procedures and the unique Palabora ore composition and characteristics, sorting technology was investigated at laboratory and pilot scale. It was found that a combination of optical and electromagnetic sorting could efficiently separate dolerite from the copper bearing and magnetite ores.This paper reports the findings of the laboratory and pilot scale work performed and discusses the additional benefits to the circuit."

Jan 1, 2012

By F. Sheykh-Jaberi, S. L. Cockcroft, A. B. Phillion

A coupled fluid/structure model has been developed to simulate semi-solid deformation in an industrial aluminum casting alloy, A356. Although this alloy has a significant eutectic fraction, nearly 50%, it still shows susceptibility to hot tearing. The model geometry consists of solid grains, created from a Voronoi tessellation of the domain, surrounded by liquid. The simulation is performed using the commercial codes, Abaqus Standard and Abaqus CFD. The solid model calculates the velocity, stresses and distortions in response to an applied uniaxial strain, and transmits them to the fluid-flow model, which computes the velocity and pressure fields in the liquid. It was shown that grain size and configuration, fraction solid and fluid properties all affect the semi-solid deformation behaviour.

Jan 1, 2014

By T. Saksala

In this paper, the embedded discontinuity approach is applied to finite element modeling of rock fracture. A rate-dependent constitutive model based on the embedded displacement discontinuity theory is developed to describe the mode I, mode II and mixed mode fracture of rock in tension and compression. The bulk material is described as linear elastic until reaching the elastic limit. Beyond this limit, a ratedependent exponential softening law governs the evolution of the embedded displacement jump. The present approach incorporates the rock heterogeneity by random description of the mineral texture of rock. Moreover, the inherent initial microcrack populations of natural rocks are accounted for as randomly oriented embedded discontinuities. Numerical examples demonstrate the model behavior in uniaxial compression and tension. The effect of loading rate and confining pressure is tested as well in 2D numerical simulations. These simulations show that the model captures the main features of rock in confined compression and uniaxial tension. The developed method has the computational efficiency of continuum plasticity models. However, it has an important advantage of accounting for the orientation of introduced microcracks.

Jan 1, 2015

By G. W. Diehl, G. A. Griffiths

"Gentlemen, one week ago, I attended the University of Minnesota's Annual Symposium on Mining, in Duluth. A good part of this symposium was dedicated to mill linings of rubber.At this symposium, three mining companies published results from long time full scale tests with rubber linings in mills at four different mines. These were the Republic and Empire Mines of Cleveland Cliffs Iron Company, the Groveland Mine of Hanna Mining Company and the Eagle Mountain Mine of Kaiser Steel Corporation. These papers will be printed in due time and I will not endeavour to relate their full contents, let me only say that in three of the plants, the linings were found to be very economical compared wi.th steel, and that these three are converting over completely to rubber linings, while the fourth, Empire Mine, reported no economical results as far as the shell lining goes, whereas the grates showed promise of becoming economical. The authors of the Cleveland Cliff's paper, however, stated that design improvements in the rubber lining possibly could result in an economical lining also for Empire Mine.That rubber linings in mills, in most cases, show better wear life than steel linings, is known by most of the audience. But, one thing that has not before been disclosed by the endusers is the effect of rubber linings on the grinding economy. All three papers mentioned above reported no change in capacity or grind and two of them reported a decrease in power consumption per ton ground. Hanna Mining reported an average decrease over a three year period for one mill of over 10%. This, of course, puts the economy of a rubber lining in a completely new light. Finally, a point of interest at this meeting was that all three papers emphasized the design aspect, Thus the industry has acknowledged what I believe to be a very important fact - the design of a lining is often more important than the material it is made of."

Jan 1, 1970

By A. Zangooi, J. A. Finch

"A frother analysis technique based on the formation of a colored solution with UV-VIS absorbance proportional to frother concentration over a certain range has been developed. The calculation of concentration requires the comparison of the sample absorbance at a selected wavelength with a linear calibration (frother concentration vs. absorbance) constructed with values collected from solutions of known concentration (standards) at the same wavelength. It has been found that concentration ranges for preparation of standards can vary widely. An integration of our experiences into a databank can offer some guidance on the selection of standard concentrations. The databank includes results from the analysis of 37 chemical reagents, commercial frothers, and natural oils used in research work or at industrial sites. Grouping frothers by similar chemical structure or origin provides a good basis for selecting the standards to approach the maximum absorbance range for the spectrophotometer in use.INTRODUCTIONA technique to determine frother concentration on samples of industrial milling streams based on formation of a colored solution with UV-VIS absorbance proportional to frother concentration has been developed. The concentration is determined by comparison of its absorbance, at some selected wavelength, with those obtained by processing a series of solutions of known concentration (standards), at the same wavelength. It is desirable to have linear calibration (frother concentration vs. absorbance) over the widest concentration range. The upper concentration can be restricted by the instrument, as there is a maximum detectable absorbance (minimum transmittance), which can be reliably sensed by the UV-VIS detector (in most cases maximum absorbance is 3)."

Jan 1, 2016

By K. A. Foxford, D. A. Polya, R. P. B. Hebblethwaite

"A variety of techniques for interpreting systems of mineralized echelon veins is discussed using examples from Panasqueira and SW England. As aids for exploration and mine planning, and as a tool for ore reserve evaluation, particular emphasis is placed upon establishing vein morphology in the third dimension, and upon understanding vein dilation and propagation histories. Special attention is also placed upon investigating vein thickness and spacing relationships, and upon understanding vein segmentation. The relevant data for these techniques are all readily obtainable from stope and core sources.The vein systems described were produced in host-rock sequences that underwent incremental dilation in response to fluid overpressures, and individual veins display evidence for mineral infilling synchronous with their propagation. Echelon vein geometries resemble those reported from igneous dikes and sills: vein walls are stepped and veins are divided into segments arranged in echelons. Changes in vein geometry, from arrays to composite structures, reflect both the evolution of the vein system with time, and the changes occurring between the margins (arrays) and core (composite structures) of the system. These characteristic morphologies can be used to infer vein propagation and fluid injection trends, proximity of neighboring veins, and the shape of the system as a whole. The techniques are applicable to systems of echelon veins produced under tensile conditions in rocks where faults were absent at the time of vein formation, and where subsequent deformation has been minimal. Further work is required to assess the application to echelon vein systems formed within more complex tectonic regimes."

Jan 1, 1995

By Bian Xue, Wu Wenyuan

High quality, mono-dispersed, hollow CeO2 microspheres with high surface area were produced by a spray pyrolysis method at 700oC. CeCl3 was used as the raw material of the process rather than Ce(NO3)3 because the latter is relatively difficult to obtain in industrial quantities. X-ray diffraction and electron microscopy results confirm the high quality synthesis of hollow CeO2 microspheres with narrow size distribution, good mono-disperse, and good reproducibility. The process of the formation of mono-dispersive CeO2 microspheres was investigated by chemical dynamics and a possible mechanism is proposed. This simple method for synthesis of CeO2 microspheres is easily scaled up to fabricate other metal oxide nanostructured materials at industrial scale.

Jan 1, 2014

By D. Laguitton, D. Cimon

"BILMAT is one of the most powerful algorithms in existence for material balance computation in mineral processing flowsheets. It is based on a hierarchical decomposition coupled with the Lagrange multipliers method widely reported in the literature. Flowrates can be calculated optionally for pulp, solid or water. Assays are adjusted for a variety of subnetworks, such as assays of the solid as well as assays of fractions of the solid called level 4 data (l: pulp, 2:solid and water, 3:assays of solid, 4:assays of classes of solid).BILMAT4 is a new implementation of BIU1AT that operates in a new microcomputer environment and makes the method more accessible than ever. Its main features are a full-screen colour editor allowing graphic flowsheet drawing and data entry with automatic error checking. Mass balance equations are automatically generated by analysis of the graphics and corresponding data, thus relieving users from the error-prone definition of networks. Sensitivity analysis is performed to assess confidence intervals of computed flowrates and adjusted assays.BILMAT4 incorporates an option for gold leaching circuits where the element to be balanced appears in both the solid and liquid phases with negligible effect on the mass flows of solids. Recoveries are computed in all streams. This program is currently released by CANMET as part of the CAMP collection for Computer Aided Mineral Processing. A complete sample run of the program is discussed."

Jan 1, 1989

By M. Lahtinen, B. Saxén, M. Latva-Kokko

The conventional jarosite precipitation process with neutralization by zinc calcine is widely utilized in the zinc industry. However, it has a significant drawback of causing losses of valuable metals like zinc, lead and silver to the jarosite. This comes mainly from the content of these metals in the calcine used for neutralization. As the zinc plants today want to maximize metal recoveries and minimize the amount of residues, this matter has become more and more relevant for zinc producers. Outotec developed and patented in early 2000 an improved version of the jarosite precipitation process in which the need for neutralization can be minimized, thus the metal losses to the jarosite also can be minimized. At the same time, the iron content of the jarosite increases and the amount of produced jarosite is smaller. The main feature of this process is to start the precipitation from ferrous iron after having reduced all the iron by zinc concentrate in a separate step before jarosite precipitation. Iron is then oxidised back to the ferric form simultaneously with jarosite precipitation. By this method, the formation of sulphuric acid is only half that compared to the conventional method and the need for calcine for neutralization can be avoided. High mixing and oxygen dispersion capability are needed in this jarosite precipitation process. Such capabilities are found in the Outotec OKTOP® reactor series. High performance reactors are not only needed to generate high quality precipitates, but also to maximize oxygen utilization; i.e., to minimize operation costs. Outotec’s latest development in this area is the OKTOP® plant product in which not only the reactors, but also all the accessories are designed, manufactured and delivered by Outotec. One responsible supplier ensures efficient and fast delivery and can provide mechanical and performance guarantees for the entire plant unit.

Jan 1, 2016

By Chri Rule

"This paper tells the story of the rapid commercial application of stirred milling technology at Anglo American Platinum’s many Concentrators. The first stirred mill – a 10 000 litre IsaMillTM; the largest at the time, was commissioned in late 2003. The project development work was presented at SAG 2001. This operation was “proof of concept” and vindicated the decision to scale up the technology; allowing a rapid and extensive roll-out of mainstream regrind mills as well as several further flotation concentrate regrind mills, over the next six years.Currently 23 stirred mills are in operation with 64 MW of installed drive capacity – this paper describes the projects’ roll-out and the significant results achieved to date. Many operational problems have been solved along the way, some of these will be described. The introduction of the technology has seen a step change in metallurgical results and progressively decreasing operating costs."

Jan 1, 2012

By I. Osvath, I. Gombköto, G. Mucsi, Z. Molnár

"In the present research, a deposited brown coal fly ash was used as raw material for geopolymer. The reactivity of the fly ash was altered using mechanical activation, which is one of the promising methods to improve bulk and surface reactivity. The mechanical activation experiments were carried out in a high energy density mill using 5 m/s circumferential speed, and various residence times (1, 3, 5, 10, 15 and 60 min). The effect of mechanical activation on particle size distribution was measured by a laser particle size analyzer and structural changes using FT-IR. Geopolymer samples were prepared from mechanically activated fly ash with an alkali solution. The progress of geopolymerisation was monitored using an Isothermal Conduction Calorimeter. The heat flow curve obtained indicated that reactions were more prominent and started much earlier in the mechanically activated samples. This observation is further supported by the compressive strength results which also improved in geopolymers using mechanically activated fly ash. Based on the obtained results, it can be inferred that mechanical activation is a possible way to enhance the reactivity of fly ash and consequently properties of resulting geopolymers.INTRODUCTIONCoal fired power plants generate fly ash and slag in huge amount worldwide, about 780 million tons/year (Heidrich et al. 2013). Due to the relatively low utilization rate, enormous quantities of these wastes are landfilled in ponds. The fly ash is the finest grained particle fraction of the solid ash, which is transported with flue gas, and removed by electrostatic or bag filters. The fly ash has pozzolanic activity, it does not react with water, but in the presence of calcium hydroxide solution hardens and solidifies, producing a reaction product practically insoluble in water (Opoczky, 2001). The most important property of the fly ash regarding geopolymerization is its reactivity, which depends on the chemical and phase composition, the dispersity (specific surface area, particle size distribution), and the morphology of the fly ash particles, and determined by the physical properties and chemical composition of the fly ash. Geopolymers concerning their chemical structure are polysialates, where the sialate (silicon-oxoaluminate) network is built up from the bonds of Si-oxide and Al-oxide by sharing oxygen atoms (Davidovits, 1988)."

Jan 1, 2016