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By A. M. Christie

Acknowledgements The following account has been compiled mainly from records and maps of Eldorado Mining and Refining (1944), Limited, hereinafter called the Crown Company. This work was done under the supervision first of R. F. Murphy, Chief Geologist, and later of E. B. Gillanders, Eldorado Mine Manager and Manager of Eldorado Exploration Division. W. F. James and B. S. W. Buffam are consulting geologists. Since 1946, S. N. Kesten has supervised geological work for the Company in the Goldfields area. Where maps of Eldorado properties have been included in this paper, the name of the geologist who examined the property is acknowledged on the map. Outline of General Geology The geology of the area is described in the Goldfields and Martin Lake preliminary maps of the Geological Survey and accompanying Paper 49-17. In brief, the Tazin series of Precambrian age, consisting mainly of sediments with minor interbedded volcanics and basic intrusives, is intruded and replaced by granite, now generally gneissic. The late-Precambrian Athabaska series of conglomerate and arkose, with interbedded basalt and andesite flows, rests unconformably on the older rocks. All these rocks are cut by small diabase dykes. The geological terms used in this paper and in the accompanying figures are standard with the exception of the term 'mafic rocks'. These include all the basic or dark coloured rocks of the Tazin group, such as amphibolites, biotite schists, and chlorite-epidote rocks (greenstones), whether they be of extrusive, intrusive, or sedimentary origin.

Jan 1, 1949

By M. Javier

Mining is most vital to our civilization. The current model of extraction technologies was designed without an expiration date and therefore generates environmental effects that are severe. Mining results-effects have been traditionally accepted and promoted around the world since Agricola described mining. Mining’s extractive technology is outmoded and standardized and inflicts negative results-effects on nature. Those results are liabilities dimensioned in legacy and type of nature able to provide to the next generation. In order to design, build, and transform mining effectively we must ask: What is the vision of mining? Mining has exhausted its antiquated mindset of over 200 years. Now it merely pilots us into crisis. The challenge today is to resolve the socio-environmental conflicts globally with a radical transformation of the mining business at its core. This paper illustrates that old mindsets must be radically updated or the concept of mining will continue to be trapped. Changing the mindset will enable discourse toward a new destiny. These changes will change mining for the better. We are able to evolve and get different results than in the past by pursuing a new legacy to live in harmony with nature for many more years. INTRODUCTION Minerals are supported by the law of conservation of mass. They have the unique characteristics of being finite, exhaustible, unsustainable, and have an unlimited recycling. Minerals are also hard to find because we have explored and virtually exhausted the whole crust of this planet. Orebodies that used to be considered world class are almost exhausted. In the short-term, it would be almost impossible to find new world class orebodies unless they could be extracted from the ocean, the moon or other planets like Mars. Mining is designed to extract minerals for profit and to keep civilizations functioning. Subsequently, mining has a social issue that is an economic issue. Thus, mining must be seen as a real and urgent subject matter that must be protected in thought and in fact. The actual mining extractive technologies produce disequilibrium in nature that has unknowable effects in the course of time. History is filled with the negative consequences to nature due to the model of mining. The evidence of these effects from mining’s model is apparent in repetitive liabilities around the world. The effects negatively impact nature without any consideration to how these impacts will manifest themselves in the future. This model of mining is widespread and extolled in every corner of the planet because it is old and familiar and although wasteful and outdated, we do not want to expend financial resources from profit or elsewhere to explore newer ideas, methods, or technologies that would help us keep a sustainable harmony between extraction and nature. We need a new vision for mining today and to explore in what way academia can and must play a social role in the teaching of mining methods. We need to question why we continue to support the old model of mining and to ask ourselves what prevents us from updating and modernizing the method of mining to meet the current needs not just of civilization but the urgent needs to undo some of the damage to the earth. This paper hopes to develop a method to change our minds about how we conduct the business of mining in order to control the destiny of it.

Jan 1, 2019

By Cyrus W. Field

Chemical, mineralogical, and petrographic data have been obtained for suites of plutonic rock samples from the Guichon Creek Batholith of British Columbia and the Mineral-Iron Mountain-Sturgill Peak- Cuddy Mountain-Peck Mountain areas of western Idaho. Intrusions at these two geographically separate localities represent composite plutons ranging from early gabbro through quartz diorite to late grano- diorite and more silicic-alkalic phases. They are early Mesozoic (200 m.y.) in age, and contain porphyry-type mineralization in close spatial and temporal association with late-stage intrusions of porphyry, aplite, pegmatite, and (or) breccia. Country rocks are eugeo-synclinal assemblages of metasedimentary and metavolcanic greenstones of Permian, Triassic, and Jurassic age. The petrochemical evolution of these intrusions, and the effects of subsequent hydrothermal alteration and metallization, are illustrated by standard ternary diagrams of the major oxide and mineralogical data. Samples plotted on an AFM diagram suggest a calc-alkaline magma trend. However, their distributions on NKC and Qz-Kf-Pf diagram show well-defined trondhjemitic (Na20-rich) and tonalitic (quartz-rich) variants to this trend, which are similar in part to those reported for mineralized island arc plutons of the northern Caribbean and southwest Pacific, but which contrast markedly to those for continental plutons of the Bingham District, Boulder Batholith, districts of southern Arizona, and elsewhere.

Jan 1, 1975

By Dick Minnitt

Large-scale variability in process plants and process control can be identified and controlled through disaggregating the overall variability in a process stream. Conventional statistics and Statistical Process Control (SPC) fail to address the concept of stream heterogeneity, therefore fail to identify and distinguish between the various sources of variability in a process stream. A modified set of 445 data from a process plant is used as an example to explain the benefits of variography in process control. Large-scale variability, usually in the form of product composition cycles and chemical cyclic variations may be manifest throughout a sampling system or a process plant, but this type of variability is most easily discernable in one-dimensional process streams. The Moving Average is a powerful tool for identifying large and small scale variability and cyclical behaviour in process streams, while the variogram is a custom built tool that allows the components of variability to be identified and resolved. The positions in the variogram at which the different variance can be read and the nomenclature of these types of variability is described. The transfer of variances converted to standard deviations to the Control Charts, allows an operator to appreciate the appropriateness of Upper and Lower control and specification limits. The overall contribution of the various sources of variability is represented in a pie diagram.

Jan 1, 2007

By A. L. Irwin

THE problem of compensation for labour is probably the oldest and most complicated one in history. The wage that a man receives is possibly the most concrete thing he gets out of his job and, rightly or wrongly, is generally considered by him to be the most important item in connection with his daily work. How today workers in an equitable way has been the study of industrialists for many years, and a great number of ideas have been tried out in an effort to arrive at a reasonable solution of the question. The idea of establishing a measuring stick for various types of work has intrigued industrial management for a long time and, after considerable study, the principle of Job Evaluation has taken form unti1, at the present time, it is becoming increasingly useful to industry at large. Job evaluation is a plan which is used to determine the relative worth of occupations by means of arbitrary measuring scales. These scales are developed for individual industries and are generally 'tailor made' for each particular case. There are as yet no absolute methods of measuring the work done by human beings and, as a result, one has to depend on comparative values to arrive at conclusions. However, job evaluation has provided us with a basis of negotiation for wage rates which is more satisfactory than mere guess work or persona! opinion. It supplies a common ground for discussion which is understandable by all taking part and ensures that thinking with regard to wage setting is carried out along standard lines.

Jan 1, 1943

By H. W. Breathitt

World demand for phosphate rock has increased significantly in the past fifteen years. Prior to the early 1960's, most of the world production was obtained from Florida, North Africa, and Kola. As the 1960's arrived, new mines in North Florida and Eastern North Carolina, as well as expanded production in the Western United States, .increased domestic production. Many new mines overseas have also become significant. This includes countries such as Senegal, Togo, Israel, Spanish Sahara, and Jordan. Limited production, often as by-products, has been noted in South Africa, Brazil, and other countries. In recent years, and even recent months, we have learned of many new areas being considered as potential sources of phosphate rock. This includes Australia, Saudi Arabia, Mexico, Colombia, and Brazil. Many other developing countries have discoveries and are considering their new deposits, often with difficult beneficiation problems, as potential sources of phosphate. These factors all relate to expanded world, population and the demand for more fertilizer products to produce food. In this paper, four areas of the world with different types of phosphate deposits are briefly reviewed to contrast the ore beneficiation problems to Florida procedures--long considered the "standard" of the industry, at least for most of the United States' domestic production. Agrico has three large operating mines in Florida with total production capacity exceeding seven million tons per year. Here, pebble phosphate (+14 mesh material) is produced without the use of flotation, whereas all of the material finer than 14 mesh is subjected to flotation beneficiation to upgrade into high grade concentrates.

Jan 1, 1977

By T. Copland

"The decreasing availability of resources amenable to surface operations has led to increasing numbers of underground mines, with trends indicating this will continue into the future. As a result, there is a need for additional optimization processes and techniques for underground mines, with many analogous methods having already been developed for surface mining. Current methods for design and optimization of stope boundary selection and scheduling mainly involve heuristic methods which focus on a single lever. Individual optimality may be approached, but globally optimal results can be obtained only by an integrated, rigorous approach. In this paper we review previous methodologies for stope boundary selection and medium- to long-term scheduling and highlight the need for an integrated approach. Previous integrated approaches are reviewed and an improved modelling system proposed for shorter solution times and greater applicability to mining situations. Randomly generated data-sets for gold-copper mineralization are used to investigate the model performance, describing solution time as a function of data complexity.IntroductionThe increasing need for mineral resources is driving an increase in underground mines. Lower grade mineralization with larger amounts of overburden is becoming economically viable due to technological advances; however, the software and tools available for strategic underground mine planning are not well developed. Advances in the methods used to determine underground layouts and scheduling must occur to ensure underground mining is as optimized as open pit operations, as underground mining involves many more technical restrictions.The process of determining stope boundaries and scheduling is an example of an aspect of underground mining amenable to optimization (Topal and Sens, 2010). The current industry standard for medium- and long-term planning for sublevel stoping (SLS) is to exclusively determine stope outlines and then determine an appropriate sequence and schedule accordingly. This process violates the concept of optimality as integrating the constraints imposed by pre-determining stope outlines does not allow for considerations in scheduling to influence boundary planning (Ataee-Pour, 2005). An integrated planning process that combines both stope outlines and scheduling would approach the optimal solution and hence generate more value for operations. This investigation specifically deals with the underground sublevel stoping (SLS). Other underground mining methods such as block caving, sublevel caving, and room and pillar mining have unique characteristics and therefore require specific stope boundary/production scheduling considerations."

Jan 1, 2016

By G. F. Vander Voort

The accident at Unit No. 2 of the Three Mile Island nuclear reactor (TMI-2) on 28 March 1979 was the worst nuclear accident in US history and crippled the nuclear industry. An international Vessel Investigation Project was formed to assess the integrity of the vessel. However, it was not possible to remove specimens from the lower head until January?March 1990. Fourteen of the fifteen specimens removed by electrical discharge machining were from under the debris pile that accumulated on the lower head due to melting of approximately 19 000 kg (45%) of the core. Specimens were previously cut from the lower head of a cancelled reactor of very similar size and design destined for Midland, Michigan. These specimens were subjected to controlled heating cycles with peak temperatures from 800°C to 1100°C for periods of 1 to 100 minutes. The initial study qualitatively compared the structures in the 15 specimens from TMI-2 to the control specimens from the Midland lower head. The writer used the same specimens and employed microindentation hardness traverses, electron microprobe analysis, and selective etching followed by quantitative metallography (by image analysis) to obtain a far more detailed description of the thermal exposure experienced.

Jan 1, 2013

By A. Desbiens, M. Maldonado, R. del Villar, Aguilera. R.

This work details the application of a multiple model approach to estimate frother concentration in flotation processes. The methodology consists of identifying a set of linear dynamic models representing the effect of gas rate on the collection-zone gas holdup at different known frother concentrations (calibration step). An adaptive law is then obtained using Bayes' rule to evaluate the conditional probability that each model represents the observed system behavior. In this way, a frother concentration estimate is calculated as a weighted sum of model probabilities and their associated (known) frother concentrations. Experimental results conducted in a two-phase system using Dowfroth250C are promising. Modeling and analysis for MIBC frother are also provided.

Jan 1, 2009

"Research on the control of exposure to respirable contaminants in mine atmospheres is conducted in five areas; 1) control of dust generation, 2) dilution, dispersion and collection of dust in mine airways, 3) characterization of dust particles, 4) interaction of dust and lungs, 5) relationship of mine environment, geology, and seam characteristics to dust generation and mobility. The distribution of research findings to the mining industry, to government agencies, and to scientists at other universities is accomplished in several ways.A data bank of respirable dust samples displaying a wide range of characteristics (low volatile, medium volatile, high volatile, silica fireclay, rockdust) has been established by the Center. This data bank is being utilized by Center researchers in a suite of medical, scientific, and engineering tests (FIGURE 26).The Center has honored requests for educational and informational materials from several sources, including MSHA and CANMET who received information on Center generated software and used the Center's expertise in developing a computer program for particle distribution model (DISFIT).The Generic Mineral Technology Center for Respirable Dust has organized two dust conferences on respirable dust, the Coal Mine Dust Conference, held at West VirginiaUniversity, Morgantown, West Virginia from October 8-10, 1984 and Respirable Dust in the Mineral Industries: Health Effects, Characterization and Control, an international symposium on Respirable Dust in the Mineral Industries held at The Pennsylvania State University, University Park, Pennsylvania from October 14-16. 1986. These conferences were co-sponsored by the U.S. Bureau of Mines, Mine Safety and Health Administration, National Institute for Occupational Safety and Health (NIOSH), and the American Conference of Governmental Industrial Hygienists (ACGIH). On August 23-26, 1988, the VIIth International Pnuemoconioses Conference was held in Pittsburgh, Pennsylvania. While not a sponsor of this conference, researchers in the Generic Mineral Technology Center for Respirable Dust had significant participation with sixteen (16) papers presented (see Volume 8 of this series for abstracts and papers). These conferences provided a significant forum for the exchange of ideas on dust research and the interchange of research findings. The proceedings from these conferences are available from NTIS and ACGIH.In sum, significant benefits to mine worker health have resulted and should continue to result from the synergistic scientific, engineering, and medical research in respirable dust (FIGURE 27). As always, an important objective is the rapid dissemination of the results of this research to industry. Video tapes and the Bureau's Technology News series have been a very effective means of USBM technology transfer. Individual no-cost subscriptions to the Technology News series are available from the U. S. Bureau of Mines, Branch of Technology Transfer, 2401 E Street, N.W., Washington, DC, 20241."

Aug 31, 1989

Lead blast furnace water-jacket stability was investigated by examining samples from the Port Pirie Lead Smelter. The compositions of the phases formed in the samples were analysed using Scanning Electron Microscopy (SEM) and Electron Probe X-ray Microanalyser (EPMA). Phase equilibria analysis and thermodynamic modelling was undertaken using FactSage with latest thermodynamic database for the slag/matte/metal/speiss/solids multi-component Cu2O–PbO–ZnO– Al2O3–CaO–MgO–FeO–Fe2O3–SiO2–S major and As–Bi–Sb–Sn–Ag–Au minor elements system. Results indicated that the stability of the water-jacket steel wall without freeze-lining is influenced by formation of the complex Fe-rich speiss phase at critical As concentrations. The integrity of the furnace walls with freeze-lining is critically dependent of the stability of the oxide-based freeze-lining which is dependent on various factors including most critical one—the proportion of solids determined by the slag chemistry and fluxing. Thermodynamic modelling of the lead blast furnace operation indicated limiting thermochemical conditions for the water-jacket stability. Factors and controls critical to the water-jackets integrity are discussed.

By T. Takayama Filho

Votorantim Metais Zinco is a smelting facility which produces SHG zinc, zinc alloys, sulfuric acid, liquid SO2, copper sulfate, cadmium metal and silver concentrate. It is located at Juiz de Fora, Minas Gerais State, Brazil. This facility has been operating since 1980 and its current capacity is 95,000 tonnes of zinc per year, using mostly imported sulfide concentrates.The plant uses the conventional roast-leach electrowinning (RLE) process, in which iron is removed from the circuit as jarosite. The residues generated by the RLE process, which amount to about 200 t/day (dry weight), were until 10 years ago, deposited in tailing ponds having no impervious lining. More recently, jarosite and other wastes have been deposited in a properly built reservoir, but this is reaching its maximum capacity. In order to decommission these disposal operations and to reclaim the sites in an environmentally acceptable manner, Votorantim Metais concluded in 2004 a rehabilitation project for the old tailings pond and prepared detailed plans for managing the current and future disposal of jarosite-bearing residues. This paper describes the procedure for removing iron from the hydrometallurgical circuit and discusses the past and current status of the residue disposal sites, as well as the future challenges related to the environmentally acceptable handling of iron residues.

Jan 1, 2006

By Albert Tasias, Daisy Jiménez

La gestión de riesgos mediante barreras, conocida como metodología Bow Tie, permite acompañar el día a día de las operaciones y está adquiriendo mayor relevancia debido a su forma sencilla de describir los peligros a través de un diagrama, en donde se pueden ver las causas y las consecuencias. Asimismo, lo interesante de la metodología son las barreras, que evitan que el peligro o las consecuencias se materialicen, para lo que cuentan con un responsable que debe gestionar y reportar su desempeño. Este trabajo realiza un análisis de la metodología Bow Tie, a través de un glosario de términos, la descripción del proceso, su aplicación actual y las ventajas y desventajas asociadas.

Sep 20, 2019

By L. E. Veki, S. M. Luukkanen, J. P. Karvonen, J. O. Leppinen

Today there is a consensus that xanthate adsorption on sulfide minerals is primarily controlled by redox reactions occurring at specific potentials on these semi-conductive minerals. Consequently, it is possible to control xanthate adsorption by controlling electrochemical conditions in the system by using oxidizing and reducing agents. The scope of this study was to investigate the possibilities to increase the selectivity of Cu-Fe-Zn ore flotation by applying electrochemical control in the conditioning of the flotation feed. In this work, mild steel grinding in a nitrogen atmosphere was used as the basis to provide a negative starting potential and minimize the amount of oxidation products on sulfide mineral surfaces. To study how different potential levels affect flotation results, a controlled conditioning procedure was utilized maintaining potential at a desired level by titrating the pulp with air. Xanthate adsorption kinetics during conditioning was examined by taking pulp samples for spectrophotometric analysis and laboratory flotation tests were conducted for samples that underwent the controlled conditioning procedure in the potential range of -200mV to +200mV vs. SHE. A clear correlation was detected between chalcopyrite recovery and the potential during controlled conditioning indicating that there was a constant increase in chalcopyrite recovery when the potential was shifted to more anodic values. It is possible that utilizing potential control in the conditioning stage, a smelter grade copper concentrate can be achieved directly in rougher flotation without cleaning stages. Conditioning in favorable conditions had significant positive effects on flotation selectivity of chalcopyrite. The improvement in copper concentrate grade being predominantly caused by the depression of pyrite. By applying the controlled conditioning procedure pyrite recovery in rougher flotation was reduced even low as under 1%, while in the tests without controlled conditioning, pyrite recovery varied between 7.5 – 65.7%. The result of this work indicate that affecting collector adsorption by electrochemical control in the conditioning stage can provide significant improvement in sulfide mineral flotation and industrial applications could lead to decreased chemical consumption, reduced equipment and maintenance costs.

Jan 1, 2018

By L. M. English

A basic model has been developed to help assess methane control needs for longwall mining of coal in gassy areas. Rather than depending upon reservoir and rock mechanic theory, it uses an empirically-determined gas emission rate as an input and operates on the assumption that, within a specific region and zone, gas emissions will be relatively equivalent for uniform incremental volumes of gob created by mining. The computer program divides longwall panels into segments, keeps track of the face advance, and generates emission rates and volumes for both the entire panel and for individual zones within the panel by summing values for all undermined segments. This model can aid the determination of the number, size, and location of vertical wells or other methane control applications that are needed for gob gas control.

Jan 1, 1998

By D. Moradkhani

Copper metal has important role in the basic industrials, as if it did not exist, modern human life would not develop! Copper leaching, as the first step, is important step in copper production processes. In this research, efficient factors on the leaching have been investigated. For this reason, four efficient factors on leaching namely pH, liquid to solid ratio (L/S), temperature and time, as independent variables, were optimized using response surface (RSM) with D-optimal. A quadratic equation was used to create response and contours. According to the results from analysis of variance (ANOVA), the value of determination coefficient (R2=96.77%) indicates that the model was good fit. Optimum experiment condition also was found: pH of 1, L/S of 8.24, temperature of 26.06 ? and time of 43.64 min. At this condition, the maximum recovery of copper was equaled to 92/38 in which good desirability achieved.

Sep 1, 2012

By L. A. Alcorn, H. E. Camargo, G. Gwaltney

"One of the most pervasive diseases in the mining industry is noise-induced hearing loss. The exposure of miners to noise levels above the permissible exposure level results in hearing loss in approximately 80% of coal miners by retirement age. In this context, the U.S. National Institute for Occupational Safety and Health (NIOSH) is conducting research to develop noise controls for longwall mining systems, which are used to extract half of the national underground coal production.From field measurements, previous research determined that the dominant sound-radiating components at the shearer of a longwall system are the two cutting drums used to remove coal. Due to the dimensions and complexity of longwall mining systems, the NIOSH project developed a validated finite element model of the cutting drum to use in predicting the sound radiated by the drum due to the excitation forces experienced in underground operations. This same model will be used to develop engineering noise controls for the drum. The excitation forces arise from the interaction of the cutting bits and the coal and are transmitted to the cutting drum through the bit holders. Due to the adverse conditions at the face, and a lack of instrumentation approved for underground use, the operational coal cutting forces have not been assessed before. To this end, NIOSH, in collaboration with Michigan Technological University, developed a self-contained, intrinsically safe instrumented bit to measure these forces.This paper describes the development of the instrumented bit and the measuring of operational coal cutting forces at three working coal mines. The measurements revealed that the forces have a flat spectrum, representative of the impact nature of these forces, up to around 100 Hz. Above this cutoff frequency, the force magnitude decreases at a rate proportional to the inverse of frequency squared."

Jan 1, 2014

By A Roshal

It is anticipated that many future uranium mines in Australia will be using the in situ leaching mining process. It is fair to say that close to one third of uranium production will be generated by this method, whilst the other two thirds will fall on the uranium generated from hard rock mining and other mining methods, such as traditional open cut mining. For other types of deposits the in situ leaching mining method will remain the best technological, commercial and environmental alternative. It is important to identify and prevent all risks involved in uranium mining. The expertise in this subject is limited. Over the years there was only one mine using the in situ leaching process for uranium extraction in Australia. Computer simulation of propagation of leachate during and after the uranium in situ leaching is a crucial factor, not only for addressing the environmental concerns, but also for the most efficient recovery of the deposit. The decontamination can be modelled for a period of up to 100 years, with the acid neutralisation forecast for a period of up to 400 years. The results of the modelling are paramount for definition of the reserves, efficiency of the mining method and the environmental impact statement. The accuracy of the hydrogeological modelling and carefully selected environmental management program enables a mining company to quantify and minimise the impact of the mining activities on the regional aquifer and to prevent environmental disasters. In the study, the completed hydrogeological model allowed the client, the authorities and the community to make an informed decision about the environmental impact of the in situ leaching of uranium. In particular, the model proved that neither during the mining, nor during the neutralisation the toxic elements would interact with the local catchment area.

Jan 1, 2008

By X. P. Guo

In this paper the test results of flotation of the kyanite ore from a Chinese mine are described. The objective of this work is to determine effective recovery process to obtain kyanite concentrate with high quality and high recovery for a new concentrator design. The valuable minerals of the ore are kyanite, garnet and magnetite, contents of them are 14.0%, 5.9% and 1.2%, respectively. The gangue minerals are mainly biotite, feldspar and quartz, contents of them are 33.8%, 17.8% and 25.6%, respectively. The kyanite in the ore contains a little iron. In laboratory flotation tests the factors affecting the flotation such as slime, alkalinity of pulp, and flowsheet configuration are studied. The interference of biotite on kyanite flotation as well as selective flotation of garnet is examined. On the basis of above-mentioned results the flowsheet of ore treatment comprising de-sliming, mica flotation, low intensity magnetic separation of magnetite, high intensity magnetic separation of garnet and coarse biotite as well as flotation of kyanite is pre-sented for comprehensive recovery of kyanite, garnet and magnetite. The kyanite concentrate con-taining more than 59% Al2O3 is obtained with a kyanite recovery of 70.0%. The contents of Fe2O3and biotite in kyanite concentrate decreased from 2.02% and 5% to 1.30% and 1%, respectively. The disadvantage of low kyanite grade in raw ore is compensated by accessory recovery of garnet and magnetite in the ore.

Jan 1, 2014

By Ki-Bok Min, Seokwon Jeon, Seung-Beum Choi, Taehyun Kim

"In order to investigate anisotropic characteristics of Boryeong shale in Korea, which clearly shows transverse isotropy, a series of experimental tests were carried out. Using Brazilian test, five elastic constants and tensile strength of the shale were evaluated. Elastic constants were determined by iterative procedure and in order to perform this procedure, constitutive model was modified to fit the experimental condition. The anisotropic ratios of elastic constants were evaluated and the applicability of the methodology was assessed. Apparent Brazilian tensile strength profile was investigated and the ratio of the maximum to minimum tensile strength was estimated. Results showed that the tested rock type had low to moderate anisotropic characteristics.INTRODUCTIONMechanical, thermal and hydraulic characteristics of many rocks vary according to direction, which is known as inherent anisotropy, and it is originated from stratified and/or foliated structure of intact rock and discontinuity of rock mass. Anisotropy is one of the long standing issues of rock mechanics field and it has to be taken into account in several engineering fields such as civil, mining and petroleum engineering. An anisotropic medium has 21 independent elastic constants without any assumption of symmetry. If a material has any symmetry, the number of elastic constants required to define its behavior reduces and eventually two constants are necessary if it has complete symmetry, which is known as isotropy. An anisotropic medium that has remarkable planar structure due to its stratification and foliation such as bedding is often called as a transversely isotropic medium. Transversely isotropic model is frequently adopted in many applications especially for sedimentary rock formation and five elastic constants are required to establish the constitutive model."

Jan 1, 2015