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By Andrea Lisjak Bradley

Clay shales are currently being assessed as possible host rock formations for the deep geological disposal of radioactive waste. However, one main concern is that the favourable long-term isolation properties of the intact rock mass could be negatively affected by the formation of an excavation damaged zone (EDZ) around the underground openings. The goal of this thesis was to develop and validate a mechanically-based model of the deformation and failure process of a clay shale, namely Opalinus Clay (OPA), with particular focus on the influence of anisotropy on the short-term response of circular tunnels. To achieve this goal, a hybrid continuum-discontinuum numerical approach was developed in combination with new field measurements from the Mont Terri underground research laboratory. The response of OPA during the excavation of a full-scale emplacement (FE) test tunnel was characterized by geodetic monitoring of wall displacements, radial extensometers and longitudinal inclinometers. The deformation measurements indicated strong directionality induced by the combined effect of in-situ stress field and bedding planes striking parallel to the tunnel axis, with the most severe deformation occurring in the direction approximately perpendicular to the material layering. Computer simulations were conducted using a newly-extended combined finite-discrete element method (FEM/DEM), a numerical technique which allows the explicit simulation of brittle fracturing and associated seismicity. The numerical experimentation firstly focused on the laboratory-scale analysis of failure processes (e.g., acoustic activity) in brittle rocks, and on the role of strength and modulus anisotropy in the failure behaviour of OPA in tension and compression. The fracturing behaviour of unsupported circular excavations in laminated rock masses was then analyzed under different in-situ stress conditions. Lastly, the proposed modelling methodology was applied to the aforementioned FE tunnel to obtain unique insights into the EDZ formation process around emplacement tunnels for nuclear waste. The calibrated numerical model suggested delamination along bedding planes and subsequent extensional fracturing as key mechanisms of the damage process potentially leading to buckling and spalling phenomena. Overall, the research findings are already having a direct impact on the preliminary design process of an underground repository for nuclear waste in Switzerland.

Jan 1, 2015

By French D

In presenting this paper may I preface my remarks by recognizing the presence here to-day of the many delegates from the overseas mining communities throughout the world. That is to say - those delegates not representative of Companies resident in Australia. This does not mean that my comments following are directed solely to the Australian exporter - far from it. The Company which I represent is internationally based. The experiences we have had in dealing and negotiating with our good friends the mineral cargo shippers vary very little in any operational area. However for the purposes of this exercise this address is based on some of our experiences within the Australian trade scene with the emphasis on the fact that we believe it has application to all trading areas.

Jan 1, 1989

By Brad R. Blair

This paper will review impacts on longwall design and ground stability assessment due to advances in mine automation and sensing technology. Several new approaches to the prediction and monitoring of longwall panel and gateroad stability have recently become mature, and are ready for application in problematic ground control situations. These methods are revealing significant detail regarding deformation and failure mechanics of critical underground structures. Examples of how these technologies have worked successfully will be given, and applications for the use of these tools for cost-effective engineering design and monitoring will be suggested.

Jan 1, 1996

By N. Jayaraman, V. Srikant, A. Radhakrishna

Addition of a 500 MW unit to the existing units at Ramagundum Thermal Power Station requires blasting of large volumes of rock very close to sensitive installations like Turbo generator, Generator transformer and Power cycle equipments. Levelling of the areas and excavations for footings are, therefore, to be carried out cautiously. The existing sensitive installations should be protected against ground vibrations and flyrock. The paper describes the details of a few of the many blasts carried out successfully wherein the ground vibrations were restricted and flyrock was avoided.

Jan 1, 2003

By Clifford B. Farris

Introduction Shale Mining Problems The mining problems an oil shale operator will face are largely determined by the process. Candidate oil recovery processes are surface (above ground processing of mined oil shale), modified in situ (underground with some shale removed), and true in situ (completely underground with no shale removed). The shale removed for modified in situ (MIS) is generally processed by surface techniques. The mining problems are different for each category. Fig. 1 depicts the diversity of western shale deposits. Mining for surface operations will employ underground mining techniques in common use but the scale will be larger. A typical oil shale operation is expected to require 75,000 to 250,000 st (68 000 to 226 800 tons) a stream day of crushed oil shale. This is above the upper limit of current mining operations. Major problems include: (1) lack of good engineering design properties for oil shale, especially when interbedded with saline minerals at depths below 1,000 ft (305 m); (2) presence of water, hydrogen sulfide, and methane in some areas; (3) necessity for mine disposal of as much retorted oil shale waste as possible; and (4) control of environmental impacts of mining. Portions of the oil shale deposits in Colorado, Wyoming, and Utah and significant portions of the Devonian shales in the eastern U.S. are adapted to surface mining. No major technological problems are apparent outside overburden thicknesses up to 1,000 ft in the West. However, numerous political and environmental difficulties have arisen. One major oil shale developer cancelled a planned surface mining operation and currently is pursuing a modified in-situ plan. The eastern shales are closer to the surface than the western, but suffer from many of the same environmental and political problems. Modified in-situ operations face much more severe mining problems than surface efforts. Because the mined stope (called an in-situ "retort" by processors) acts as a retorting process vessel subject to gas flow, combustion, and temperatures between 1,500° and 2,000°F, mining is under highly restrictive limitations. This processing method involves removing between 20 and 40% of the shale deposit and then blasting the roof and walls into the mined space, where the oil is recovered by retorting. Major problems are: (1) swell factor severely limited; (2) need for consistent size distribution of blasted shale; (3) even filling of stope (in-situ retort) by blasted shale with consistent permeability throughout; (4) scaleup of blasting techniques, after optimization; (5) protection of retort pillars and roof during and after retorting; (6) prevention of groundwater percolation; (7)use of ANFO explosive in wet holes; (8) disposing of surface-retorted shale waste in stope; and (9) restoration of site. True in-situ operations are less well developed than surface or MIS processes. No actual mining is done, as the true in-situ processes generate permeability in the highly

Jan 9, 1980

By Clifford B. Farris

Introduction Shale Mining Problems The mining problems an oil shale operator will face are largely determined by the process. Candidate oil recovery processes are surface (above ground processing of mined oil shale), modified in situ (underground with some shale removed), and true in situ (completely underground with no shale removed). The shale removed for modified in situ (MIS) is generally processed by surface techniques. The mining problems are different for each category. Fig. 1 depicts the diversity of western shale deposits. Mining for surface operations will employ underground mining techniques in common use but the scale will be larger. A typical oil shale operation is expected to require 75,000 to 250,000 st (68 000 to 226 800 tons) a stream day of crushed oil shale. This is above the upper limit of current mining operations. Major problems in¬clude: (1) lack of good engineering design properties for oil shale, especially when interbedded with saline minerals at depths below 1,000 ft (305 m); (2) presence of water, hydrogen sulfide, and methane in some areas; (3) necessity for mine disposal of as much retorted oil shale waste as possible; and (4) control of en¬vironmental impacts of mining. Portions of the oil shale deposits in Colorado, Wyoming, and Utah and significant portions of the Devonian shales in the eastern U.S. are adapted to surface mining. No major technological problems are apparent outside overburden thicknesses up to 1,000 ft in the West. However, numerous political and environmental dif¬ficulties have arisen. One major oil shale developer cancelled a planned surface mining operation and currently is pursuing a modified in-situ plan. The eastern shales are closer to the surface than the western, but suffer from many of the same environmental and political problems. Modified in-situ operations face much more severe mining problems than surface efforts. Because the mined stope (called an in-situ "retort" by processors) acts as a retorting process vessel subject to gas flow, combustion, and temperatures between 1,500° and 2,000°F, mining is under highly restrictive limitations. This processing method involves removing between 20 and 40% of the shale deposit and then blasting the roof and walls into the mined space, where the oil is recovered by retorting. Major problems are: (1) swell factor severely limited; (2) need for consistent size distribution of blasted shale; (3) even filling of stope (in-situ retort) by blasted shale with consistent permeability throughout; (4) scaleup of blasting techniques, after optimization; (5) protection of retort pillars and roof during and after retorting; (6) prevention of groundwater percolation; (7)use of ANFO explosive in wet holes; (8) disposing of surface-retorted shale waste in stope; and (9) restoration of site. True in-situ operations are less well developed than surface or MIS processes. No actual mining is done, as the true in-situ processes generate permeability in the highly

Jan 1, 1980

By M. R. Saharan

A brief overview of rockburst control measures is presented. The paper then elaborates on one key rockburst control measure, which is known as destress blasting. A historical background of the technique is presented in order to understand different aspects of its field application. The publication enumerates key aspects of the technique as being used in practice in South Africa and North America. The paper also presents an analysis of three case studies in order to demonstrate difficulties associated with the field application of distress blasting in hard rock mines.

Jan 1, 2006

By W. J. Miles

Many years ago, a relationship was established between dust inhalation and pneumoconiosis. Since then, various government agencies have regulated crystalline and amorphous forms of silica material in the workplace. In 1987, the International Agency for Research on Cancer (IARC) classified crystalline silica as a probable carcinogen. With this listing, crystalline silica became a regulated substance under the Hazard Communication Standard. The minerals and chemicals industries have responded in various ways. They have: • developed worker and user training programs and literature; • labeled products with appropriate warnings; • continued to implement dust reduction programs; and • developed meaningful epidemiological studies of workers. • begun development of reliable analytical methods for measuring crystalline silica at the 0.1 % threshold level; Background Silicosis historically has been the major health hazard resulting from exposure to crystalline silica. Silicosis is the scarring of the lung from excessive exposure to crystalline silica. It has been recognized as an occupational disease for more than 2000 years, since early Greek physicians noted the respiratory problems of miners, stonecutters, and quarrymen who were exposed to excessive quantities of mineral dust. During the industrial revolution, the incidence of the disease was greatly increased by the use of machinery that increased dust levels. Subsequently, the need for dust control was recognized and measures were instituted. Silicosis is characterized by progressive breathlessness on exertion and develops over the course of years. Xray images of the lungs show

Jan 1, 1990

Adsorption of Alkylammoniums in the Interlayer of Montmorillonite and its Effect on the Viscosity of Organo-Montmorillonite Gels

Sep 13, 2010

By U Singh

This paper presents the evolution of the studies and strategic plans to extend the life of operations at the Savage River iron ore project in north-western Tasmania. The current Life-of-Mine (LOM) plan for the Savage River operations is based on a series of open pits. Drilling has confirmed high-grade extensions of the magnetite resource at depths that exceed practical limits for open pit mining. Grange Resources Limited, the owner of the operation, is investigating underground options – not only to extend the LOM plan but also to maintain peak production at a reduced operating cost while reducing greenhouse gas emissions into the future. What makes this project unique is that it requires introducing a productive and cost-effective mining method to exploit a challenging geotechnical and geometrical orebody in an area of high rainfall. To support the study efforts, the development of an exploration decline, underground drilling programs, and an exploratory drive excavated into the orebody for geotechnical investigation was key to providing the necessary data for a pre-feasibility study (PFS). This paper describes the pragmatic approach and processes to developing the underground mining options study through data collection and then integrating these options into the open pit plans to optimise an overall strategic plan for the Savage River operations. The learnings for operators from this experience are how the technical and pragmatic approaches were aligned to develop the strategic plans, and the importance of timely investment in gathering the necessary data.

Mar 29, 2023

By S. G. Shabestari, S. Saeidinia, P. Mokarian

"The experiments were conducted to investigate the influence of various process parameters in rotary degassing of aluminum alloy AS5U3G. Degassing was carried out by use of argon inert gas. The flow rate of the gas was investigated in the range of 12 to 21 L/min., 350 to 500 rpm rotor speed, 6 to 12 minutes degassing time, and 755°C to 780°C melt temperature. Degassing efficiency was evaluated through measuring the density of RPT samples. By optimizing the process parameters, RPT sample density was increased up to 2.73 g/cm3, which guaranties the production of high-quality aluminum castings. Tensile strength and elongation were increased considerably by degassing process. Scanning electron microscopy (SEM) shows small size and well-distributed microporosity. IntroductionOne of the major problems associated with the casting of aluminum alloys is the formation of gas porosity. Aluminum and its alloys are very susceptible to hydrogen absorption. Because solubility is much lower in solid state than liquid state, hydrogen atoms leave their position during solidification and combine together to form hydrogen molecules. These micrometer- scale cavities, called microporosity, cause the reduction of mechanical properties, particularly strength, ductility, fracture toughness, fatigue resistance, pressure tightness, and corrosion resistance (Laslaz, 1991; Jorstad and Rasmussen, 1993; Sigworth and Wang, 1994; Korasani, 1996; Anson and Gruzleski, 1999; Zhang et al., 2000). To avoid these problems and produce good quality castings, it is necessary to remove hydrogen from the melt. Several methods are available for degassing aluminum melt. One of them is a rotary degassing system using inert gas, e.g. Ar or N2. Various thermodynamic and kinetic factors govern the removal of hydrogen from molten aluminum (Anderson, 1987; Sigworth, 1987; Pignault, 1993; King and Reynolds, 1995). These are some parameters that affect degassing efficiency. Some of them are discussed here and some are examined in this project."

Jan 1, 2004

A brief review is given of the history of the Colliery to date together with the reasons for the development of an additional seam.Investigations into the quality of the coal ami its suitability for the production of metallurgical coke and determination of the economic mining limits and coal reserves are discussed. The commencement of mining operations and the inter-seamarrangements necessary for the disposal of coal won are described with the stages in the opening out of the seam itself and the reasons for the installation of a 48-in. trunk conveyor belt. Choke and manning of face equipment are considered and also the work of secondary development and pillar extraction.It is concluded that with modern face equipment and conveyor belt lines, concentrated mining followed by immediate extraction of pillars is practicable and is giving excellent results at Burwood Colliery.INTRODUCTIONBurwood Colliery, the total holding of which now comprises some 3,140 acres of land and 1,450 acres of sea leases, has mined the Borehole Seam since 1883. The early work took place from Nos. 1 and 2 shafts at Glenrock Lagoon and later on at Nos. 3 and 4 shafts at Whitebridge to which the centre of operations shifted in 1893, shaft sinking at this latter area having commenced in 1888.As all the early operations were confined to the Borehole Seam, reserves of coal on this horizon had been considerably reduced by the mid 1930's, so a cross measure drift was driven to the Victoria Tunnel Seam which is about 300 ft. above the Borehole Seam, and fully mechanized coal winning commenced from the second seam in 1938. Subsequently this cross measure drift was extended to the Borehole Seam and complete mechanization of the south-west sections of this seam achieved by 1945.Four track mounted mechanical units were put into operation in the latter area and these worked in a southerly and...

Jan 1, 1958

By Dirección General de Promoción y Sostenibilidad Minera del Ministerio de Energía y Minas

El artículo da cuenta de la situación del sector al 2019, año en el que pese al panorama adverso se superó la meta de inversiones con más de US$ 6 100 millones ejecutados. Se reportan asimismo las importantes mejoras efectuadas en la normativa minera para actividades de exploración, como son —entre otras— la ampliación por 3 años de la vigencia de la Ley N° 27623 y el adelanto de inicio del proceso de consulta previa para actividades de exploración. El artículo incluye la nueva cartera y el Mapa de Proyectos de Exploración Minera, actualizados a febrero 2020.

Feb 28, 2020

By L Avalos, F Melo Miranda, J Misle, M Ingwersen

"Los Pelambres, majority owned by the Chilean company Antofagasta Minerals, is one of the leading producers of copper and molybdenum in the country. It is located high in Andes Mountains, over 3000 metres above sea level, 316 km from the nation's capital, Santiago.The maintenance service supplied to Los Pelambres over the past 13 years has evolved to the point that FLSmidth now provides an integrated service crucial to the management of their customer's assets. The contract initially involved specialty mechanical, electrical and instrumentation maintenance and has developed to encompass maintenance planning and plant control systems.The integrated partnership has delivered excellent results in the areas of improved availability, reliability and return on investment. The operation is now amongst the industry leaders in plant availability.The integrated maintenance service has delivered: An increase in plant availability from 93%, in the first year, to 96.5% today, generating approximately $50 million additional income per year, Quality work procedures, Process and equipment improvements, Major shutdown planning involving more than 700 personnel, 6000 parts and over 2 000 discrete activities.The ongoing success of the partnership requires a high level of understanding between both companies. A commitment to maintain a long term sustainable relationship, based on a ""win - win"" culture, is the key to this success. In this regard Los Pelambres has been a pioneer in establishing and developing such relationships.This case study will share the lessons learnt, the measures taken to improve performance and the best practices adopted during the 13 year evolution of the maintenance service partnership.CITATION:Misle, J, Melo Miranda, F, Avalos, L and Ingwersen, M, 2013. Integrated maintenance services at the Los Pelambres Mine in Chile - The lessons learnt and best practices developed from a long-term sustainable relationship, in Proceedings MetPlant 2013 , pp 296-331 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jul 15, 2013

By S. H. Lorain

This paper, which describes lode gold mining in Idaho county, Idaho, is one of a series on western mining districts being published by the Bureau of Mines. It describes mining and milling practices, gives costs, and discusses transportation, climate, power, labor, and other conditions that affect them. The materiel upon which the paper was based was gathered during a field survey in the summer of 1937.

Jan 1, 1938

By John H. Wright

The United States Antarctic Program (USAP), through its principal support contractor Raytheon Polar Services Co. (RPSC), has recently completed a three-year project comprising nearly 936 m (3,071 ft) of undersnow utility tunnels at Amundsen-Scott Station, South Pole, Antarctica. The tunnel serves the new station facilities that are currently under construction. It houses the piping that conveys fresh water from current and future water well sites, as well as waste water to repositories in abandoned wells. The undersnow tunnels permit year-round access for system operations and maintenance. The network of tunnels is entirely unlined and unsupported. And, for the most part, it maintains a rectangular cross section of 1.8-m-wide x 3-m-high (6 x 10 ft).The tunnel runs from 6 to 14 m (18 to 45 ft) below the surface. Eight 1-m- (3.3-ft-) diam raises bored from the surface serve the network as emergency escapeways.

Jan 1, 2002

By Henry Kreisinger, J. F. Barkley

This book is one of a series of publications being issued by the Bureau of Mines for the purpose of disseminating information in regard to the methods by which the fuels in this' country may be used most efficiently. A knowledge of the temperature of the gases in boiler settings and in other commercial apparatus using heat tends to develop improved designs of apparatus and better methods of operation, thus reducing waste of fuel. The following pages present, for the benefit of those designing, operating, and testing such apparatus, information as to the accuracy of temperature measurements made under certain conditions and the corrections that can be safely applied.

Jan 1, 1918

Effects of High Pressure Grinding Rolls on Platinum-Bearing Ores and the Flotation Response as Compared to the Conventional Ball Mill Three major PGM ore types from the Bushveld Complex of South Africa: Merensky, UG2 and Platreef were comminuted with the use of the high pressure grinding rolls (HPGR). The influence of the feed characteristics and the various operational and design features of the HPGR on energy consumption, throughput, mineral liberation and PGM flotation recovery were investigated. The test work variables included two feed top sizes of 12 mm and 6 mm, specific grinding forces ranging between 3 - 7.5N/ mm2 and zero gaps of 1.5 mm and 3 mm. The results show that the influence of the HPGR operational and design features on energy consumption, throughput, mineral liberation and PGM recovery are ore dependent. The size reduction-specific energy relationships show that the most energy efficient utilisation of the HPGR for Platreef ore was at the lower specific grinding force of 3N/mm2 and the zero gap at 3 mm. For Merensky and UG2 ore on the other hand, the most energy efficient operation was at the higher specific grinding force of 7.5N/mm2 and the zero gap of 1.5 mm. At a specific energy input of 3 kWh/t, reduction ratios (F50/P50) of 6.5, 3.8 and 10 were obtained for Merensky, UG2 and Platreef, respectively for feed top sizes of 12mm. Further application of the HPGR as a pregrinding stage to a ball mill showed a 25 - 30 per cent increase in throughput for Merensky and UG2 ore. Batch flotation tests performed on selected samples appear to indicate that ore comminuted with the ball mill had superior grades compared with that ground with the HPGR. However, Merensky and UG2 ore comminuted at different HPGR operating conditions showed distinctions in PGM recovery. Platreef on the other hand did not appear to show any differences. Therefore, this study highlights the significance of ore type and operating variables in HPGR applications with regards to energy efficiency, throughput and PGM recovery.

Sep 13, 2010

By Andy Schroeder

Located in Hamilton, Ontario Canada, Berminghammer Foundation Equipment, is a manufacturer of advanced foundation equipment with 30 years of experience. The company is represented in more than 20 countries world wide, maintains an extensive Research and Development team, and has earned a reputation for finding the most practical solutions to the most challenging projects. The vertical travel lead, referred to as "VTL" system, was first developed and patented by C.W. Bermingham in the 1970's. This lead system was developed in response to the fundamental limitations of either a fixed lead or hanging lead system. The fixed lead system is well suited to level job sites with few obstructions and has the advantage of faster positioning of the lead, the hanging lead is very adaptable to different elevations and batter piles but takes much longer to position. Therefore the Vertical Travel Lead was developed to combine the advantages of fixed leads, fast and accurate positioning, with the ability to adjust the height of the lead base up or down. The VTL lead is connected to the boom by a sliding connection which allows the lead to be elevated or lowered below grade. The advantages of the VTL system were recognized by many foundation specialists and they have become the Industry standard in Canada , US Railway Construction , and many parts of the USA.

Jan 1, 1997

By M Orunesu Preiata

The Odysseus Project is part of the high-grade Cosmos Nickel Complex that lies 30 km north of Leinster. The Odysseus definitive feasibility study (DFS) was approved by the Western Areas’ board in October 2018. Early works commenced in January 2019 with rehabilitation of the existing underground infrastructure. In June 2022 Western Areas was acquired by IGO Ltd. The project is now well advanced to meet its target of first concentrate. The project included the construction of a haulage shaft. The design of the hoisting equipment and the shaft barrel evolved from the initial DFS design stage to the final execution, as the data were made available from the initial investigation to the data gathered during execution (although this did not change from its initial concept). The design philosophy for the haulage shaft incorporated, from the beginning a multidisciplinary approach with inputs from three main areas involved in such projects, namely excavation techniques, geotechnical assessments, and infrastructure construction. This interaction is a fundamental component for the success of such a critical project. In fact, each of these three areas influences each other in a cyclical manner, triggering a continuous review of the project inputs and outputs, while maintaining the original project goals: the design of an infrastructure able to deliver the desired throughput. The throughput dictates the infrastructure that needs to be built, which in turn controls the size of the shaft. The key assumption applied to this is that the rock mass can accommodate the excavation void, and the excavation technique with its tolerances and limits that ultimately need to be verified back with the initial assumptions used for the infrastructure design. The aim of the paper is to present a case study of the experience gained with the Odysseus hoisting shaft and to propose a possible logic path for similar projects elsewhere.

Mar 29, 2023