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By A. W. Chan

"An interactive computer simulation model of conveyor systems used in oil sands mining has been developed to aid in the selection of mining equipment and the evaluation of operating policies. The materials handling links between supply points, such as bucket-wheel excavators and draglines, and demand points such as bins and extraction plants are modelled in such a way that the conveyor model can be interfaced with any combination of these equipment submodels. Detailed calculations of the power demand of each conveyor section based on operating characteristics and conveyor design parameters are included to permit the close monitoring of energy requirements. Various interactive features are incorporated so that an operator can not only monitor, but also control, the mining operations in the model and experiment with different operating strategies.IntroductionThe interactive simulation model of conveyor systems described in this paper is one of a number of detailed computer models being jointly developed by the National Research Council and Canstar Oil Sands Ltd. on the mining equipment and operations used in oil sands mining. Reference I presents an overview of this whole series of models, their interrelationships and the underlying motivation for their development.A network of conveyors constitutes one of the practical ways for transporting mined material in an oil sands plant. The materials handling links between supply points, such as bucket-wheel excavators, bucket-wheel reclaimers and bins, and demand points such as dumps, bins and extraction plants can be represented by a series of interconnected conveyor sections. For example, the fluctuations of the feed rate at the bucket-wheel excavator, the flow of ore material through the conveyor network and the arrival of this material at the extraction plant can be simulated."

Jan 1, 1982

By W. M. Moon, Hugh G. Miller, C. -S. So

"Digital image processing and enhancement techniques have been applied to airborne gamma ray spectrometry data from Sudbury, Ontario. These results have been correlated and compared with the available geological maps to evaluate their usefulness for identifying lithological units. Digital processing allows the correlation of various data sets, and different combinations of images can be tested and viewed as a composite image. Composite images with pseudocolours provide an opportunity to analyze and correlate information that is not otherwise apparent in individual images. Principal component analysis has been applied to the gamma ray spectrometry data to evaluate their efficacy and relative information contents of the measured and computed data. The results of this study indicate that the combined radioelements image (obtained by combining the radioelement image and the ratio images) is effective for defining areas of relative concentration of a specific element in near surface materials. Furthermore, the composite radioelements image (produced by combining three separate radioelement images) and composite principal components image reflect large-scale lithological variations. IntroductionThe Sudbury area is a unique geological structure located in the southern Canadian Shield (Fig. 1). Because the area hosts economically significant nickel-copper deposits (Pye et al., 1984), it has been surveyed in great detail by geological and geophysical methods. In order to obtain meaningful geological infonnation about the Sudbury area, several studies have been carried out with the application of innovative mathematical techniques for geophysical modelling, and attempts have been made to integrate the multisensor geophysical data available for the area (e.g. Gupta et aI., 1984; Moon et al., 1988; Singh et al., 1993). The main objective of this paper is to apply digital image processing and enhancement techniques to airborne ganuna ray spectrometry data in order to determine their usefulness for regional geological mapping."

Jan 1, 1994

By T. Tsutsumi, S. Kukino

"During the diametrical compression test, the tensile stress generated near the loading plate is influenced by the contact area between the loading plates and specimen. However, very few studies have determined the contact area. Theoretical or analytical models have shown that for an orthotropic material (i.e., with material properties that differ along each of three mutually orthogonal twofold axes), the maximum tensile stress is generated at the center of disk when the angle of the principal material direction to the loading direction is close to ?/4. The maximum value is almost constant, regardless of the contact area. Conversely, the maximum tensile stress is generated near the loading plate when the angle between the principal material direction and loading direction is small. The maximum value decreases as the contact area increases. Therefore, in the latter case, the influence of the contact area on tensile strength measurement of is significant.In previous studies, the distribution of stresses applied on the loading plate is assumed to be a uniform load. In reality, the applied stress is highest at the center of loading plate and seems to decrease with distance from center. The applied load disappears at the edge of loading plates. In this study, in order to satisfy this boundary condition on the loading plate, the cosine curve is adopted as the distribution of load applied on the loading plates in a theoretical model of the diametrical compression test. Furthermore, the elastic solution using boundary conditions shown in this study is used to obtain the tensile stress distributions on the loading axis for an orthotropic circular plane. These distributions are compared with empirical results obtained under uniform loading with a loading plate or concentrated loading in previous studies."

Jan 1, 2015

By Sadan Kelebek, Gerhard W. Heinrich, Peter F. Wells, Peter J. Whittaker

"Based on plant mineralogical data & circuit modelling, a pilot plant campaign was conducted at Strathcona Mill to identify options for improving the performance and operating flexibility of the copper-nickel separation circuits. Emphasis was given to options for combined treatment of the two feed streams (primary nickel ore rougher concentrate and copper ore circuit concentrate) to obtain more flexibility in the use of existing column flotation capacities. The pilot test results demonstrated that circuits which incorporated preconcentration prior to column flotation gave the best metallurgical results. Maximum column carrying rates were also related to the preconcentration. Predictions that increased circulating loads from the column scavengers would improve copper-nickel separation performance were confirmed.IntroductionThe copper-nickel separation circuits at Falconbridge's Strathcona Mill produce a high grade (>30% Cu) copper concentrate most of which is treated at the Falconbridge Kidd Creek smelter near Timmins. The remaining nickel concentrate which still contains approximately 20% of the feed copper is combined with other lower grade nickel/copper concentrates and shipped to the Falconbridge nickel smelter. The separation is required because of the limited capacity for copper processing in and downstream from the nickel smelter. Since no nickel is recovered at present in the Kidd smelter, the challenge is to minimize the nickel content of the copper concentrate.At present there are two independent separation circuits treating the rougher concentrates from the copper and nickel circuits as shown in Figure I. The minerals treated are mainly chalcopyrite and pentlandite but there is up to 25% of the copper present as cubanite in the copper ore. The circuits were kept separate because the flotation rates and froth characteristics were very different, probably because of the presence of cubanite and the large difference in the concentrate grades feeding the circuits."

Jan 1, 1995

By G. Heinrich

Size by size recoveries and pentlandite liberation data from image analysis were used to evaluate plant tests of pentlandite flotation and pentlandite/pyrrhotite middlings flotation from pyrrhotite in a circuit treating low grade magnetic intermediates at the Strathcona Mill. Raising the pH with lime gave improved selectivity for liberated pentlandite but there were major losses of middlings unless the circuit was pulled hard indicating the need for finer regrinding. However, size by size recoveries at the normal regrind showed that, while the pentlandite recovery improved in the finer ranges, the pyrrhotite recovery also increased leading to little selectivity in any size range. A much finer regrind gave greatly improved selectivity in all size classes suggesting that 'surface polishing' as well as liberation effects were being seen. Using liberation data from image analysis of the products, surface polishing accounted for over 99 % of the improvement in selectivity. Unreasonable recoveries of more highly liberated particles were observed for liberation analysis by volume fraction but showed the expected trend in recovery when the analysis was based on surface liberation. The surface liberation data showed that the improved pentlandite recoveries after finer regrinding were to more than 90 % caused by improved liberation with the remainder contributed by surface polishing effects. The practical implications of this work are that i) the comparison of particle grades with product grades allows to estimate the effect of regrinding on co-flotation/entrainment, ii) surface liberation models should be used for evaluating recoverabilities by flotation and iii) regrind circuits may be set up to ensure that all particles go through the mill or that only the coarse fraction is reground depending on the surface scrubbing found to be required.

Jan 1, 1993

By M. Doucet

The introduction of high-nickel anodes to CCR in 2006 resulted in an increase of nickel in anodic slimes. Removal of the nickel in these slimes to below 3.0% is necessary in order to prevent slag viscosity problems in the subsequent pyrometallurgical step. A lower specification of 0.5% was chosen in order to minimize Ni losses to the slag and to recover this nickel as NiSO4. A 2-stage autoclave process, which was patented by CCR in 1992, was chosen to treat the high nickel slimes. Laboratory and plant?scale tests were performed in 2004 in order to validate the results of this process with the present slimes. These results along with corrosion tests were used to design two brick-lined autoclaves. These autoclaves were installed in October 2006 and successfully commissioned within 8 weeks. A "Design of Experiment" test program was performed in 2006 on an alternative autoclave process that reversed the cycles in the patented process. The effects of temperature and acid content were modeled using the results. The alternative process will be validated with the new autoclaves.

Jan 1, 2007

By B. Zhu, W. E. Lee, N. Li

Al powder is used extensively as an antioxidant in carbon-containing bricks, but it cannot be used directly in water-based carbon-containing castables due to its hydration tendency. To overcome this problem, in this work, SiO2-PVA (polyvinyl alcohol) inorganic-organic hybrid coatings have been prepared via sol-gel processing, and used to coat Al powder. The hydration behaviour of uncoated and coated Al powders has been investigated in water at 60 or 100°C for 36h by examining phase and microstructural changes. While significant hydration is detected in uncoated Al powder, no obvious hydration is detected in coated Al powder, indicating that its hydration resistance has been greatly improved. Oxidation resistance of graphite coexisting with uncoated or coated Al powder was also investigated in air at 1250°C for 1.5h. The oxidation ratio of graphite coexisting with coated Al powder was similar to that of graphite coexisting with uncoated Al powder, indicating that both powders showed similar antioxidising behaviour. This, along with the much improved hydration resistance, makes the coated Al powder a potential antioxidant in carbon-containing castables systems.

Jan 1, 2004

By M. Askari, M. H. Parsa, S. Kashani-Nejad

Sarcheshmeh refractory consumption rate is about 7.5 - 8 kg/ton of the produced copper, which is almost three times higher than the other smelters practice. High destruction rate of tuyere zone refractory controls vessel productivity and operational lifetime. In this research with the aid of cold model and computational fluid dynamic (CFD), melt recirculation pattern and gas - liquid plume properties in the wide range of gas blowing conditions were studied. Results revealed that in addition to the well-known mechanical refractory destruction mechanism, fast tuyere zone refractory destruction could also be related to the cold bubble cluster formation near tuyere tips and introducing severe thermal shock to the refractory surface. Removing accretion and its strong bonds to the refractories around tuyere tip, causes refractory mechanical destruction and increases tuyere diameter. Increased tuyere diameter, in turn assists gas discharge in the bubbling regime. Air blowing in the bubbling regime result in the formation of big bubble clusters, bubble breakup and back attack occurrence which all found to have major impact on the refractory lifetime. Outcomes of this research, contributed to the plant converting management, blowing hardware and instrumentation improvement.

Jan 1, 2004

By G. W. Brooks

This short article is quite different to the general run of papers that are presented to the Institute, but no apology is offered because I consider that first-aid and mine-rescue work are of equal importance to many other subjects that are dealt with in our Transactions. Members of the Institute should be as much interested in the safety of persons engaged in the mining industry as they are in the practical methods of modern mining. We must not only do our best to conserve life and property by adopting every known device to that end, but we must also prepare ourselves so that we may take prompt and effective action when life is in danger, or when property is subject to loss. The need for such preparation in Alberta is perhaps greater than in most places where mining is carried on, and we must spare no effort to assemble at every mine men who are well trained in first-aid and mine-rescue work. The large area over which the mines are distributed renders central training stations out of the question, hence the need for local rescue-teams. Hospitals with skilled staffs, close enough to the mines to be convenient, also seem to be out of the question; therefore the greater need of a high standard of first-aid training for the people in our mining camps. The Government mine-rescue cars are supplied with the equipment necessary for training persons in this essential work and also for dealing with disasters should they occur. The question then arises: are there a sufficient number of men who are trained ? If so we can rest assured that what is possible to be done will be done. But if a sufficient number of trained men are not available much loss of life and damage to property is likely to result.

Jan 1, 1925

By R. B. Harkness

Many of us are familiar with the history of oil in the Province of Ontario, but for the benefit of those who have never heard the story I will repeat it. In 185 7 J. H. Williams, of Hamilton, an old-country Scotchman, who had the advantage of experience gained from the primitive methods used for refining the oil collected at seepages in Roumania, heard of the "gum beds" along Black creek in Enniskillen township, Lambton county. He erected a small plant in the bush and refined illuminating oil, where the village of Old Springs now stands. The labor of collecting this thick ?gummy substance from the sluggish water of the creek, prompted him to dig a well, the next year ( 1858), in the hope of obtaining a greater quantity. When his excavation reached a gravel bed on top of the rock, oil, resembling "lubricating oil of commerce", rose several feet. Several of these wells were dug and his refining business flourished. The following year the Drake well, in Pennsylvania, was drilled into rock, resulting in an oil find which encouraged one James Shaw to make a similar attempt on Black creek. With a spring-pole drill he completed his well in the spring of 1861 to a depth of 160 feet, and at that depth struck a gusher that flowed uncontrolled for several days. Great excitement followed and the village of Oil Springs had a mushroom growth. The Petrolia field was discovered in 1865. Lick followed up the Thames with a spring-pole rig testing the formations along that river and discovered the original Bothwell field in 1865. During the sixties wells were drilled in many counties in southwestern Ontario.

Jan 1, 1924

By O. Moselhi

Material can be seen as the fuel needed to execute the project from inception to completion. Material installed provides good indicators of progress achieved onsite vis-a-vis project schedule performance. It correlates well with the role of the schedule performance index (SPI) of the earned value method (EVM). Material is recognized to have a significant impact on achieved progress for physical completion of project activities. This paper presents a study on the development of material status index (MSI) in support of the EVM. Unlike the SPI, the newly developed index account for the criticality of project activities. This is carried out considering the total float of each activity, percent float (i.e. the ratio of float to activity duration) and the total float of the path on which the activity is located. MSI, can independently and jointly with SPI provide root causes behind problems encountered during project execution. In turn MSI can reveal material related factors behind the performance detected by joint interpretation of the two indices. MSI serves to provide added value in alerting management to take corrective actions. While SPI and MSI may have different values, they can jointly augment and enrich the captured project status based on EVM. To demonstrate the capabilities of the developed MSI method, it is implemented on a case study. The case encompasses the construction schedule of a hydro power station constructed in northern Quebec. Different scenarios are adapted from the real case to demonstrate a set of practical aspects of the developed index. The results generated from the analysis of the case study illustrate the useful features of MSI beyond those of the traditional SPI on two fronts; causation and the considerations of criticalities of actives.

Aug 1, 2013

By R. W. Pugh, S. L. Ma

"High carbon rods are typically used as the grinding media in rod mills. Usually an AISI I 090 grade of steel is used which provides the high hardness needed for abrasion resistance and sufficient toughness to prevent rod breakage.Work to improve performance in the past has mainly concentrated on increasing the hardness for improved abrasion resistance. This has been accomplished by adding alloys to the steel which uniformly increase the hardness across the rod section.However uniformly increasing the hardness of the rod produces a more brittle product and at high hardness l1evels can lead to rod breakage problems. Heat treatment processes can be used to selectively increase the surface hardness to high levels while maintaining the core at lower hardness levels to give a product that wears slower without breakage. AltaSteel has developed and mill tested a higher hardness heat treated grinding rodThis paper describes the development of a simple model to predict performance improvement with different hardness profiles and the AltaSteel heat-treated grinding rod process. Mill characteristics of the Endako operation are summarized and predicted performance improvements based on hardmess are compared to the approximate 25% achieved in trials running since July, 1991 at this mill. Early results of other mill trials are also presented.INTRODUCTIONAltaSteel, in Edmonton is a major supplier of grinding media. We have a strong desire to continually increase the quality and performance of our products and thereby improve the efficiency of our customers' processes. In the area of grinding rods, we wanted to produce a product with a significant improvement in wear rate. Second to energy, rod consumption usually represents the next highest cost in processing. This paper presents our development of a heattreated grinding rod that has reduced consumption by about 25% in trials to date."

Jan 1, 1993

By Chester J. Kuryliw

"The Geology of the Cochenour Willans mine, Red Lake district, was described by J. P. Nowlan in the Jubilee Volume. The complexity and intense alteration of the rocks obscured any clear relationship between ore and structure, and Nowlan recognized that future work might greatly modify the ideas then existing. This has proved to be the case. Subsequent detailed work has established the stratigraphic sequence in the Keewatin formations which are the host rocks of the orebodies, and has shown that the principal orebodies are confined to two adjoining bands of tuff.On this basis, it is now possible to map the complex structures with greatly increased accuracy. The amount of drilling and underground exploration required to find new ore has been much reduced, and indicated ore reserves are now substantially greater than at any time in the past. Daily production in 1955 averaged 187 tons per day at 0.578 ounces of gold per ton.The sequence of Precambrian events in the mine area is summarized in the following table:Intrusion of post-ore dykes.Ore formation.Intrusion of post-faulting, pre-ore dykes.Deformation: folding and shearing; alteration; faulting.Timiskaming sedimentation.Unconformity.Keewatin: volcanics and sediments, host rocks of the orebodies, described in detail in the next section.KeewatinFrom oldest to youngest, the Keewatin rocks in the mine area can be divided into six formations, which have been given local names:“Grey"" LavaA fine-grained dacitic to andesitic lava, amygdaloidal and locally containing well formed pillows. Certain areas are sheared and chloritized to a degree that makes identification difficult. The rocks are carbonatized throughout; the most persistent carbonate veins parallel the upper contact. Thickness more than 1,000 feet. (Minor mineralization, type 1 I -See section on Ore Formation)."

Jan 1, 1949

By Paul Delottinville, Maynard Hall, Henry Hillier

"An expert system application for supervisory control and optimization of the indurating process at the Iron Ore Company of Canada (IOCC) has been developed and installed in closed-loop. Prior to the installation of the expert system, the indurating machine was rebuilt and the instrumentation revamped. A Foxboro I/A Distributed Control System (DCS) was installed for regulatory control, and a new control strategy configured. The modernization of the regulatory control has resulted in significant improvement in both production rate and product quality. Expert system control was implemented in September 1996. Preliminary indications are that the expert system has further improved the consistency of product quality, enhanced fuel efficiency and increased productivity. The expert system considers both wet and dry sections of the circuit, and its optimization scheme is driven by pellet tumble index and compression strength. Statistical Process Control (SPC) rules were implemented in the expert system as part of the quality analysis and control scheme. The expert system application was developed and delivered using the Comdale Expert Optimizer (CEO), and has been in continuous closed-loop control since its installation. The system development and implementation is described, and preliminary benefits are presented..... IntroductionIn early 1996 the Iron Ore Company of Canada (IOCC) contracted Comdale Technologies of Toronto to develop and implement a real-time expert system for optimizing the indurating pelletizing furnace at our plant location in Labrador City, Newfoundland.The decision to install the expert system has been timely. Like many other resource-based industries in increasingly competitive markets, IOCC recognizes the need to find ways to improve the efficiency of our production process and ensure that product quality is maintained at the highest levels. With the Labrador City plant producing 11 million tons of iron ore pellets annually, implementing the best technology solutions to meet these objectives is critical."

Jan 1, 1998

By O. Hall

DISCUSSION AT QUEBEC MEETING MR. A. V. CORLETT: With drill holes radiating from a common point, is loading carried to the collars, and do you undertake to distribute the powder evenly? MR. R. V. PORRITT: When the collars of the holes, particularly the diamond-drill holes, are close together, two out of three holes are loaded only to within six or seven feet of the collars, and the intervening holes are loaded close to the collars. When the collars are farther apart, the holes are loaded close to the collars. No spacers are used, and the holes are filled solid with powder, this applying particularly to the diamond-drill holes, except, of course, where the collars are close together and some holes are not loaded close to the collars. MR. J. G. L. McCREA: I would like to enquire in respect to the various efforts made to reduce the cost of diamond drilling to the lowest point, what is. the relative cost of the solid bit to the standard bit? It would seem that the solid bit has the higher cost. MR. PORRITT: The non-coring or solid bit gives a slightly lower diamond cost than the coring bit. With the coring bit, the greatest diamond loss is on the inside stones, apparently due partly to vibration, but mainly to the core blocking against these stones. This condition, of course, does not apply with the non-coring bit. Our experience is that the non-coring bit, which drills out a much greater area, has a diamond consumption slightly less than the coring bit. The non-coring bit is sturdier, and is far less liable to damage in starting holes and in drilling through cracked or broken ground.

Jan 1, 1939

By Carl Sonnen

Reading the newspapers, you will know that opposition to ratification on economic grounds always points to the view that action will result in major price increases for energy (to both industry and households) with consequent severe losses of energy production and a loss of competitiveness for energy-intensive producers (i.e., in your kinds of industries). You might think of this as the ?carbon tax? fear, and you should note that many of the initial policy development experiments included variations of this theme. Analysis reported in late 2000 and into early 2002 reported reductions in energy production in the long run of between 10% and 20%. At the upper end of that view, these were the kinds of numbers reported in the Industry Canada study ?leaked? to the Press last week. The consequences of this approach included significantly uneven negative effects for some provinces (e.g., Alberta, but also Saskatchewan and Newfoundland). It had been agreed by the First Ministers of Canada, however, that the policy should not yield those results so development in recent months has focused on eliminating sector and therefore provincial ?sore thumbs?. Although an emissions trading system, which represents this type of approach and directly impacts costs of production, continues to be featured in the new or current policy and is applied to the Minerals Industries among others, it is designed to be implemented in such fashion that the costs are more moderate than before. And because the industries covered by permits are almost all price takers, there is no device for moving an increased price signal forward to ?consumers?. What this does do is even out negative effects among sectors in the economy and for provinces, but at the expense of government financial results.

Nov 1, 2002

By H. E. T. Haultain

Research is a much over-overworked word, sometimes a much abused word; the result of this has been that many who really need the word avoid it, shy away from it just as we do from that most useful word camouflage. We have not been altogether happy in our substitutes. Some years ago I spoilt a very good proposition by using the word investigation. There were those who thought that men and methods were to be investigated instead of simply processes. They expected disruption instead of co-ordination. The bad psychology up-set the scheme. The word experiment is even worse in its psychology. To the mind of the "practical" business man experiment denotes ignorance, waste of time and money and presupposes failure. It is not so long ago that the recognized way of improving the methods about a mine was to get a new manager. Until comparatively recently the average life of a boss in a mine in the West was under, rather than over, two years. Certainly was this the case in the smaller mines. Directors did not recognize that a cock-sure new boss was a greater experiment than a certain amount of feeling-his-way on the part of the old one. We always say that no two mines are the same but we are only now realizing to what extent the fine points of the game can and must be learnt on the job itself. One of the main differences between a small property and a large one lies in this study of the fine points of the game. In the early stages operation is the main point-get her going and keep her going.

Jan 1, 1924

By Phil Molloy

"In March, 1968, Skega Ruh her Liners were used to reline the shell of an 8' x 12' Allis Chalmers ball mill.This mill is used to regrind the cyanided pulp from 58i -200 mesh to 92% -200 mesh prior to this pulp passing to the flotation circuit, at approximately 450 tons per day.Before the use of rubber liners, the regrind ball Mill shell had been lined with single wave ni-hard liner!'. These liners had an average life of five years. Ni-hard end liners were used both prior to and during the use of rubber liners, as the life of the ni-hard end liners was about seven years, and it was thus felt that little economic benefit would be realized by lining the ball mill ends with rubber.The rubber lining used has a thickness of 57.15 millimeters and the square shaped lifter bars which are spaced at 14~ inch centres, have a 4"" x 4"" cross-sectional dimension.With the use of ni-hard liners, the consumption of 1 1/4 forged steel balls averaged 1.062 pounds per ton, Using rubber liners the consumption of l~"" forged steel balls increased to 1.368 pounds per ton. Also the level of the ball load which previously had been kept at approximately 18 inches below the mill discharge, had to be increased to approximately 8 inches below the mill discharge in order to effect the same grind.The initial gri4ding performance of the newly relined mill was also poor, until the leading edge of the rubber lifter bars, which were square shaped in cross-section had been worn to a rounded profile. These lifter bars were replaced after 4 years and 3 months of operation.The advantages of rubber liners in our opinion is as follows:"

Jan 1, 1974

By J. R. Maxwell

In 1970 expansion was completed increasing mill capacity from 2,000 to 3,000 T.P.D. Actual grinding capacity is 3,400 T,P,D. at a grind of 60% -200 mesh,The ore bodies are vein type, containing about 12% sulphides, with mill heads averaging 2.25% Cu, 0.015 oz.Au, and O.4O oz, Ag. per ton.Summary and Conclusions:During the period Jnnuar-1 1971 to December 1973 inclusive the use of large cells at Opeminka have shown that metallurgy is comparable to when using conventional cells, Operating and maintenance costs are lower, An on stream analyzer with reagents controlled by computer, are being assessed further.Opej1atljn Of Cells:!lo cell level adjustments are required when tonnage is adjusted 20 to 25%.Depending on mill heads and grade of concentrate reagents are adjusted to the first rougher for metallurgical control. Reagents to second rougher and scavengers are seldom adjusted as feed to this section has a maximum variation of about 0.2'~ Cu.Power – Maintenance and Space Requirement :Our total power consumption for 3,400 T.P,D. flotation circuit for operation and air supply is 280 H.P. Previous power drawn using conventional cells was 400 H.P. at 2,000 T.P.D.Total maintenance costs for flotation circuit has averaged $1,100.00 per year for the 3 years of operation, this cost should remain constant.Floor space required for cells and walkways is 2,000 sq.ft.

Jan 1, 1974

By Ki-Bok Min, Bona Park

"In spite of the applications of DEM models to emulate the elastic modulus, Poisson’s ratio and strengths of isotropic rock in laboratory scale, extensions to anisotropic rock and larger engineering scale still have many challenges to overcome such as robust verification and validation against observed field case. In this study, a discrete element modeling was performed in order to represent a transversely isotropic rock such as shale, and the upscaled model was applied to foundation and borehole problems using PFC2D. The applicability of the upscaled rock mass model was verified by an analytical solution. The DEM modeling of stress redistribution induced by an applied surface line load compares well with Boussinesq’s isotropic solution and anisotropic solution given by Bray. The borehole model with a circular opening under biaxial stress was compared with both isotropic and anisotropic solutions resulting in good agreement. The abilities of DEM model to investigate the micromechanisms accounting for complex macroscopic behaviors and to predict the macroscopic behavior are discussed.The results demonstrate that DEM modeling has the potential to be applied to anisotropic rock mechanics problems on larger engineering scales such as wellbore stability problems especially in shale formations. Furthermore, the effect of anisotropy modeled through this study may be able to explain failure behavior of anisotropic rock encountered frequently in real cases.INTRODUCTIONAnisotropy is prevalent in various types of rocks, especially in shale that contain a set of parallel bedding planes. These weak planes in various forms are sources of large deformation and low shear strength and contribute significantly to the anisotropic behavior of rocks (Amadei, 1996; Cho et al., 2012; Kim et al., 2012). As elastic and strength behavior of anisotropic rock is substantially different from that of isotropic rock, proper consideration of anisotropy is of great importance. There is extensive of experimental evidence showing the anisotropy of shale. Niandou et al. (Niandou et al., 1997) analyzed the plastic deformation and failure mechanisms of Tournemire shale were highly dependent on the orientation of bedding planes. Cho et al. (Cho et al., 2012) presented various deformations and strengths of Boryeong shale obtained from laboratory experiments. Fjaer and Nes (Fjaer and Nes, 2013) performed uniaxial and triaxial compressive strength tests using Mancos shale, and they observed that the shear sliding along the planes of weakness before the occurrence of a major failure can reduce the strength of anisotropic rock. The recent research has demonstrated that the anisotropy of rock is an important consideration in rock engineering."

Jan 1, 2015