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By Kevin Azocar, Jim Hazzard

"Slope stability analysis is performed most commonly using limit equilibrium calculations or numerical models assuming a two-dimensional slice through an infinitely long slope surface. In areas such as open pit mining, where most slope surfaces are not planar, the importance of curvature becomes important due to the economic gains associated with creating a steeper slope. With advances in computing capabilities within the last decade, three-dimensional slope analysis can be performed within reasonable time frames. Some work has been done on the potential importance of curvature on slope stability, mainly assuming homogenous materials with a circular shear-failure mechanism. However, many open pit mines are excavated in jointed rock mass where a completely different set of failure mechanisms can be seen. Depending on the geometry and radius of the pit, the curved geometry may influence the factor of safety and failure behaviour compared to a two-dimensional slice.A series of numerical analyses were performed to investigate the effect of curvature on jointed rock slope stability compared to an equivalent two-dimensional slope analysis. By using discrete element method models, the influence of joint planes and interaction between distinct blocks can be seen. With a three-dimensional model, the effect of curvature can be combined with multiple joint sets at any orientation, which cannot be seen in a single slice. Numerous three-dimensional models are created, along with an equivalent unit-thick slice. The effect of curvature on a variety of different types of failure mechanisms is observed, and graphical relationships are created to quantify the difference between the three-dimensional factor of safety and the two-dimensional factor of safety based on the degree of curvature."

Jan 1, 2015

By R. L. Eadie, J. L. Luo

The effect of plastic deformation on near-neutral pH stress corrosion cracking (SCC) also known as environmentally assisted cracking was studied by cracking rate measurements. All the tests were conducted in a synthetic near-neutral pH solution. The traditional potential drop tests using compact toughness (C-T) specimens with 2-3 mm long pre-cracks showed varying plastic deformation by rolling would increase the material's susceptibility to SCC. This was confirmed by cyclic loading tests using double notched flat tensile specimens with 200-300 µm long pre-cracks which gave the same results that the specimen with large scale plastic deformation by tensile loading had a relatively faster crack growth rate than that with only small scale plastic deformation.

Jan 1, 2005

By C. Juers

Laboratory chromate coating was applied on AM50 and AZ91D alloys and compared to phosphate-permanganate one. Evaluation of the corrosion behaviour was performed using electrochemical DC and AC methods in ASTM water D1384-87. This electrolyte was chosen because it was moderately aggressive and found to give generally good correlations with long period exposure results in atmospheric conditions. Electrochemical impedance spectroscopy was used to determine more accurately the corrosion rates from the analyses of the high frequency capacitive loop. Anodic polarization was applied in order to evaluate the pitting resistance of the different coatings. These results were correlated with weight loss data evaluated from experiments performed by immersion tests in ASTM water D1384-87 and climatic cyclic chamber tests.

Jan 1, 2006

By C. Sui, J. E. Nesset, M. Li, J. Y. Kim, S. L. Chryssoulis

"A plant study of zinc rougher flotation at Brunswick Mining was conducted using lime, soda ash and a combination of both as the pH modifiers in order to establish the effects on sphalerite and pyrite kinetics and mineral selectivity. The plant sampling and analysis was augmented by surface analysis using TOF-LIMS, SEM and XPS as well as fundamental precipitation and surface-charge studies in the sphalerite Ca/C03/S04 system.The results revealed the important role of carbonate ions in cleaning the sphalerite surface for effective activation by CuS04 to occur, and the beneficial role of combined soda ash and lime in increasing pyrite and galena depression.1.0 IntroductionThe studies reported in this paper were initiated as part of an investigation into the causes of a particularly pronounced seasonal deterioration in metallurgical performance at the Brunswick Mining concentrator during the summer of 1995. The concentrator treats a complex base metal ore having a typical feed composition of 9.0% Zn, 3.5% Pb, 0.4% Cu and 100g/t Ag at a current throughput of 9,000 TPD, although at the time of the problem in 1995, the average production rate was closer to 10,500 TPD. Zinc, lead, copper and bulk (zinc-lead) concentrates are produced with overall metal recoveries of 86% zinc, 63% lead, 60% copper and 60% silver; results which are typical of the lower recoveries associated with fine-grained, highly complex VMS and SEDEX type deposits. The main economic minerals of interest are an iron-containing (7% Fe) sphalerite, galena and chalcopyrite with the main diluent (about 60% wt) being pyrite.Figure 1 shows a simplified flowsheet of the Brunswick milling circuit while the seasonal decrease in summer metallurgy in 1995 is illustrated in Figure 2. Of significance is the rapid drop in copper and lead recovery in June while there is an apparent delay until late August-September before the zinc deterioration reaches its lowest point. A more typical seasonal effect within the experience of the authors is the reverse of the Brunswick situation, namely an improvement in summer performance thought to be associated with improved differential flotation kinetics during warmer weather leading to better mineral selectivity. The historical Brunswick experience was particularly severe during the summer of 1995 with estimated incremental losses of $10 Million for this period. The potential of the very significant economic benefits to be gained from understanding and hopefully improving the annual drop in performance led to an investigation involving the minesite metallurgical group, the Noranda Technology Centre (NTC) as well as researchers in Professor Jim Finch's group at McGill and the surface analytical services and interpretive skills of AMTEL."

Jan 1, 1998

By Mohamed Hamoud

Relative permeability curves represent an important element of special core analyses, but challenges remain in obtaining valid results and the extrapolation and use of existing permeability results is problematic. This situation is compounded in cases where core properties are altered from changes in effective stress. During the production of oil and gas reservoirs, the effective stress changes as a result of changes in pore pressure or temperature. Therefore, changes in rock properties such as porosity and permeability will occur and will consequently influence reservoir performance calculations. An experimental program was carried out to understand the behavior of dense, reconstituted sand samples at low effective stress states. Drained triaxial compression tests were set up to study the effect of stress alteration on relative permeability data through porous media. Initially, a saturation stage was performed followed by isotropic loading to bring the core sample to reservoir fluid and stress conditions. Then, while axial (deviatoric stress) loading was applied to the sample, a series of absolute and relative permeability tests was performed under steady state flow at different levels of strain during pre and post peak shearing stress. The stress-strain behavior results from the study revealed that the absolute permeability decreased during isotropic loading (compaction) and increased during shearing (dilation). However, the shape of relative permeability curve changed from contraction to dilation and showed higher initial kro and the lower initial kro respectively. The goal of this project was to understand the behavior of both absolute and relative permeability at different stresses. It is expected that geomechanical processes will be adopted for special core analyses to support the current integration of geomechanics into reservoir engineering. This will be required if, during SAGD, conventional and/or unconventional reservoir simulation, reservoir engineers implement a proper set of relative permeability data at each in situ state of stress, instead of constant curves throughout the field?s life.

Jun 1, 2012

By R. Thierbach, W. Kahnt, Oberthür. T., D. Eisenburger, V. Gundelach

ABSTRACT: The ground penetrating radar (GPR) method was used in a platinum mine in Zimbabwe by members of the Federal Institute for Geosciences and Mineral Resources (BGR). The measurements were carried out in boreholes and drifts. Electromagnetic re?ections from a fault that consistently trends parallel to the mineralization zone permitted the mapping of the economically minable parts of the deposit. An introduction is given to the geology of the studied area and the application of the GPR method. The electrical parametres of the rocks are measured in situ, the GPR measurements are displayed with radargrams, and the visible structures are explained in illustrations.

Jan 1, 2010

By Nigel Saunders, Zhanli Guo

"Quench sensitivity of heat-treatable aluminium alloys is closely related to the precipitation process taking place during quenching. Faster cooling results in less precipitation of coarse phases during cooling, leaving more solutes in the solution before ageing. An alloy in such state would be of greater hardening potential as larger amounts of hardening phases may precipitate out during ageing. Hence, to understand the quench sensitivity of an alloy, it is essential to understand its precipitation process. Precipitation is a diffusion-controlled process and the diffusion is made complicated by the so-called quenched-in vacancies. These vacancies form during solution treatment, become “excess” when temperature goes down, and annihilate during the following cooling and ageing treatments, making diffusion now a function of both temperature and time. This paper first investigates the formation and annihilation of quenched-in vacancies and their effect on diffusion. The diffusion affected by quenched-in vacancies is considered in the kinetic models to realise the calculation of TTT/CCT diagrams for aluminium alloys. The calculated CCT diagrams have been used to explain the observed quench sensitivity and age hardening behaviour of various commercial alloys. The transformation from GP zones to other hardening phases during ageing is also discussed.INTRODUCTION The heat treatment of aluminium alloys mainly consists of three stages: a solution treatment at an elevated temperature, quenching from this solution treatment temperature to room temperature, followed by an ageing treatment to allow the precipitation of strengthening phases(Davis, 1993).The following statements generally describes how quench sensitivity is observed in heat-treatable Al-alloys: faster cooling results in,(i) less precipitation of coarse phases formed at high temperature during cooling, (ii) more solutes kept in solution before ageing, and (iii) larger amounts of hardening phases being formed, i.e. a greater hardening potential. Thus, the quench sensitivity of an alloy is closely related to its precipitation kinetics."

Jan 1, 2018

By D. Nie, M. Ren, T. Mo

This paper studied the phenomenon of room temperature creep deformation at crack tip and its effect on fatigue crack growth rate of a X-70 pipeline steel using compact-tension (CT) specimen on a MTS 810 testing machine. Time-dependent deformation at the crack tip under constant load was observed in this steel at room temperature and the amount of deformation produced was seen to depend on loading rate and the magnitude of stress intensity factor. It is found that there exists a critical stress intensity factor below which the deformation decreases with time when the applied load remains constant. It is also found that the occurrence of room temperature creep obviously affects the subsequent fatigue crack growth rate. The observed behavior was explained based on dislocation theory.

Jan 1, 2005

By B. Hewitt

Murrin Murrin Operations has not had a successful beginning. Numerous reliability and operability issues many of which are the result of design decisions have been addressed through mechanical and operational changes and the CCD circuit is no exception. The decision to install, the installation and the results of the CCD1 rake-lift mechanism and feedw ell dilution system are discussed in this paper. The installation was justified on improved operational robustness and an increase in the in the underflow density of 1% (per cent w/w). At approximately the same time process modifications in the solution neutralisation circuit were implemented and these changes altered the rheology of the slurry reporting to CCD1. Since the modifications to CCD1 and the solution neutralisation circuit, the CCD circuit has averaged a 2% improvement in the circuit underflow density. The CCD1 modification was completed on time and mechanically has performed well. From a risk point of view, the central rake-lift and Turbodil® dilution system add a degree of freedom and robustness to CCD1 operation that has extended the range of operational confidence. In this respect, the modification has been a success and is complementary to solution neutralisation improvements.

Jan 1, 2004

By R. P. van Hille, A. W. van Zyl

The BIOX® culture, aiding liberation of arsenopyrite/pyrite occluded gold, is inhibited by thiocyanate (SCN > 1 mg/L); precluding the recycling of tailings water up-stream of the bioleaching circuit. The activated sludge tailings effluent remediation (ASTERTM) process is a biological process that was developed to facilitate water recovery and treat waste water on-site (to achieve a SCN concentration < 1 mg/L) to be recycled or disposed of. The aim of this study was to investigate the effects of changing temperature and SCN loading on the SCN degradation ability of the mixed microbial population clue to seasonal temperature changes and fluctuations of SCN concentration in the waste water.

Jan 1, 2011

By Zhang. L.

Ordered intermetallic PtSb had been synthesized by arc-melted and then sintering treatment. The electro-oxidation of formic acid on PtSb was investigated at room temperature by cyclic voltammetry and chronoamperometry. The results are compared to those at a polycrystalline platinum electrode surface. It was found that PtSb intermetallic was catalytically more active than pure platinum according to the onset potential and current density. XRD and XPS technologies had been used to investigate the crystal structure and electron effect. We think formic acid decomposition on PtSb favors the reactive intermediate route and is not very much affected by the CO intermediate as compared to Pt.

Jan 1, 2005

By J. R. Johanson, A. W. Jenike

"A solid flows out of a bin provided that the outlet is sufficiently large so that stable obstructions to flow do not develop. The geometry and surface finish of a bin and the construction of the feeder determine the type of flow pattern which then develops within the bin. The pattern, in turn, affects the uniformity and consistency of the stream, segregation, caking, degradation, live capacity and the action of level measuring devices.In most bins now in operation, material flows toward the feeder through a channel which forms within the stationary solid. This is referred to as funnel flow. If the hopper of the bin is sufficiently steep and smooth and the feeder capable of drawing material across the whole area of the outlet, all the solid flows whenever the feeder is in operation; this is referred to as mass flow. Mass-flow bins are usually far superior to funnel-flow bins; their initial cost is also usually higher.The paper describes the design criteria used in deter-mining the minimum bin outlet needed for flow and the bin geometry needed for mass flow."

Jan 1, 1970

By Forrest A. Kerr

Northern British Columbia is a term which probably conveys to various individuals quite different meanings. To the average person it signifies an area of indefinite size and indefinite position which may start at Prince Rupert, Stewart, or somewhere else, and end at Alaska or .the Yukon. Many people, in their conception, fail to encompass in their mind&apos;s eye that vast tract of land lying ~o the east of the panhandle of Alaska. Few realize that the area north of an east-west line through Stewart represents more than one-third of the Province and is, of course, the part most appropriately designated as northern British Columbia. This section, more especially the northernmost 100,000 square miles, from political, geographic, and economic viewpoints stands isolated perhaps more than any other part of British Columbia. Unlike the rest of the Province, it has no coast line, being cut off from the Pacific ocean by a narrow strip of Alaska. It is bounded on the north by the Yukon, and on the east by Alberta. In the south this northernmost 100,000 square miles is limited by a divide of rugged mountainous country separating the drainage basins of the Stikine and Liard rivers from those to the south.

Jan 1, 1929

By Tong Qin, Jinxia Zhang, Fusheng Niu, Limei Bai

"The interaction between a deformable bubble and a rigid particle in viscous liquids under microgravity conditions is studied by direct numerical simulation via an Arbitrary-Lagrangian-Eulerian (ALE) method. Due to the microgravity, the bubble will stay as a sphere in the fluid without external forces and its deformation is caused by the moving particle. In this study we assume the flow field is axisymmetric and the motion of the gas inside the bubble is neglected. The particle equations and the Navier-Stokes equations for the fluid are solved in a unified finite element framework. The particle obtains an impact velocity by an external force and the impact velocity is varied over a wide range. A ‘critical time scale’ T0 was identified for the interaction process. For successful contacts between particle and bubble, the time scale of their relative motion must be less than T0.INTRODUCTIONThe particle-bubble interaction is an important process in many applied industrial domains such as water treatment, froth flotation and liquid steel purification. It is a complex three phase process in that it embraces many research areas: fluid hydrodynamics, interfacial forces, particle and bubble behaviour and solution chemistry.Derjaguin and Dukhin(1961) clarified the particle-bubble interaction by introducing three-zone model for small and medium size particles. When the particle is far away from the bubble surface, the hydrodynamic forces are dominant. The particle is driven toward the bubble surface by the particle inertial and gravity. This region is regarded as Zone 1 and the interaction in this zone is a collision subprocess. As the particle gets close to the bubble, it exits a zone where the liquid flow around the bubble surface creates a tangential stream from the upper surface of the bubble toward the rear of the bubble. This is Zone 2 which is called the diffusiophoretic zone. In Zone 3, the particle is very closed to the bubble, surface forces like van der Waals, electrostatic and structural forces are considered. Contrast to Zone 1, Zone3 can be regarded as an attachment subprocess."

Jan 1, 2016

By K. Bunney, R. Pleysier

The deportment of a suite of elements through representative gold ore processing unit operations in cyanidation has been investigated. Chromium and lead are not soluble in alkaline cyanide solutions. Arsenic, antimony, cobalt, molybdenum, selenium, tellurium and vanadium are soluble, but typically do not adsorb onto activated carbon to any appreciable extent. Silver, copper, cadmium, mercury, nickel and zinc to varying extents report along with the gold to the carbon eluate. Cadmium, mercury and zinc can report to the carbon regeneration kiln off-gases. Strontium is soluble and adsorbs on carbon where it remgins.

Jan 1, 2011

By Y. A. Topkaya

In this research work, a process was described for the recovery of copper and zinc in copper converter flue dust from the Black Sea Copper Works&apos; Samsun Smelter Plant. After characterization of a representative flue dust sample, the process included roasting of the flue dust and then leaching in dilute sulfuric acid solution. Roasting time and temperature were studied to determine the optimum roasting conditions. Sulphuric acid concentration, duration, temperature of leaching and solid to liquid ratio were the parameters studied in the bench scale laboratory leaching experiments.

Jan 1, 2007

By Chris Carr

This paper describes the process employed and the work undertaken to enable the surrender of the mine permit relating to the two tailings deposits at the abandoned Red Mountain Mine site near Rossland, BC. The first phase of the work undertaken was to provide urgent remedial work for protection of the environment, primarily through rehabilitation or replacement of surface water drainage systems. The second phase was to up-grade the water management systems to the appropriate level given their consequences of failure. The final phase of work is to ensure long term geotechnical stability of the facilities to the same level of risk. Establishment of a sustaining fund will facilitate long term monitoring and maintenance of the facilities.

May 1, 2002

By E. Ghali, C. Su, G. Houlachi

"The influence of lead ions on zinc electrowinning process was investigated by means of electrochemical noise measurements (ENMs) and cyclic voltammetry in conjunction with scanning electron microscopy and X-ray diffraction. All electrochemical experiments were performed in sulphuric acid electrolyte containing different lead ion concentrations as impurity. Lead was added in six trace levels between 0.05–0.8 mg/L in the bath. The lead content of the zinc deposits was dependent on the introduced lead concentrations. The overpotential associated with zinc electrodeposition shifted to higher values with the increase of lead concentration in the solution. An appropriate correlation was found between the different concentrations of lead in the electrolyte and the morphology of zinc deposit by ENM. The results showed that the increase of lead ion concentrations is generally accompanied with the decrease of skew and increase of kurtosis values that could be related to the morphology of zinc deposit. Effectively, the morphology changes from well-defined hexagonal platelets to large hexagonal, layered platelets and finally to non-symmetric refined crystalline structure, respectively.INTRODUCTION In commercial zinc electrowinning, zinc oxide is leached from the roasted calcine with an aqueous acid sulfate electrolyte. Then the zinc-rich solution is purified and transferred into an electrolytic cell. During electrolysis, zinc is deposited on aluminum cathode where lead-silver or pure lead is served as anode. Electrodeposition of zinc could be influenced by several parameters such as bath acidity, temperature, current density, the nature and concentration of impurities as well as additives in electrolyte. Metallic impurities play a complex role during zinc electrowinning and they can adversely"

Jan 1, 2016

By A. S. Robb

SAMPLING of an ore-body is one of the fundamentals in its exploration, development, and exploitation. It is carried out to determine the gold value per ton of an ore-shoot and the probable gold output of the refinery. Sampling also places any broken ground in one of two classes, ore or waste. The value and importance of correct sampling has been shown repeatedly in the past. On the other hand, instances could be given where those in charge of mines have not believed in sampling, and the result has been the same in every case-disaster. This has in all probability been due to assuming that good-looking, well-mineralized rock was ore. Sampling in some form might have averted this misfortune. In this essay, only the method of sampling and the estimation of ore reserves is treated. All titles, figures, and values are fictitious. None of the illustrations can be directly applied to any portion of the Hollinger mine, except Figures 1 and 2, which are included with the special permission of the Canadian Mining Journal. METHODS OF SAMPLING Hollinger Consolidated Gold Mines, Limited, has, from the very beginning of operations, carried out an extensive system of sampling, and the results of this sampling have completely governed the whole mining programme. The Hollinger discovery was made in 1909 and prospecting and exploration of &apos;the surface began at once. Four men were given jobs as samplers and they sampled thoroughly all the outcrops and all bed-rock which could be exposed to view by removing the overburden. When shaft sinking began, samples were taken at two-foot intervals. In 1912, an underground gang of six samplers was organized, and the number was increased at a rate of about two men per year as the size and extent of the workings grew. No permanent record of sampling was kept until 1919, in which year an average of 11.6 men took 28,458 samples, cutting 113,894 feet of sample. From that time until the end of 1934, the average number of samplers varied, but the total number of samples cut, and the total footage sampled, increased.

Jan 1, 1937

By Lawrence Devon Smith

"The Management and Economics Society has undertaken a survey of industry practice in the evaluation of mineral projects. The survey addresses a number of issues relating to evaluation techniques, discounted cash flow methodology, and risk. Completed during the spring and summer of2005, the results provide a record of opinion at an active and vital time in our industry.The 2005 survey questionnaire was distributed by e-mail to groups and organizations around the world. There were 22 respondents out of several hundred questionnaires distributed (we gather this small proportion of respondents is typical for such surveys). The responses, although a small number, show a consistency that suggests that the survey has captured the views of the industry. The results of the survey are summarized below in series of tables and graphs.The reader is cautioned that the results are a snapshot of industry practice at a point in time as represented by a small sampling of the industry's practitioners. These results should be viewed as indicative values."

Jan 1, 2003