Search Documents

By Axel Nitschke, Josef Arnold

Bochum’s Underground Lot 306 was characterised by a confined site and unique tunnelling methods. A highly mechanized construction concept was developed to achieve high progress rates. Bespoke backup systems for muck disposal and material supply were used. For the first time in suburban tunnelling, wet shotcrete, batched onsite, was applied. A three-storey underground car park had to be undermined with only1.5 m of overburden and had to be lifted several times by “compensation grout in.” An existing operational two-lane metro tunnel was enlarged without any major impact on train operation.

Jan 1, 2005

By Joe Roby

Rolling disc cutters are the business end of hard-rock and mixed-face tunnel boring machines (TBMs). Since their first successful employment on a TBM more than 50 years ago, disc cutter technology has constantly evolved, allowing modern TBMs to excavate very hard and abrasive rock efficiently. Disc cutters have also been employed successfully on earth pressure balance (EPB) and slurry machines, cutting rock under water and ground pressure. The range of materials excavated by machines today is broader, excavation rates are higher and cutter costs are lower than ever before, proving the value of investment in cutter development. Disc cutters are used on a range of tunneling equipment, from pipe jacked slurry micro-TBMs less than 1 m (3.3 ft) in diameter to 15 m (49 ft) in diameter, hard-rock boring TBMs. The geological conditions under which they are employed range from sands and gravels, with several bar of water pressure, to extremely hard, massive rock with UCS up to 420 MPa. Regardless of the type of machine or geology, one thing remains constant: changing worn out cutters is costly. When cutters must be changed in the middle of a tunnel, the contractor incurs the cost of downtime as well as the cost of refurbishing or replacing the cutters. In the case of catastrophic cutter failures, the project can be stopped completely for long periods, and the costs mount up rapidly while tunnel production is at a stand still. Catastrophic cutter failures include the occasion when hard-rock disc cutters are failed in groups (called a ?wipeout? phenomenon) and the operator fails to stop the machine, which results in severe damage to the cutterhead. The cause of this can be either an undetected failed cutter propagating damage to surrounding cutters or operator error in steering. Regardless of the cause, the resulting damage can take days or even weeks to repair. When cutters fail prematurely on EPB or slurry machines in certain geological conditions, it is impossible to evacuate the chamber and, therefore, impossible to get [ ] into the chamber to change the cutters. The solution is frequently an unplanned intervention shaft that must be sunk at great cost. The importance of being able to predict cutter life accurately, and in all geological conditions, cannot be overemphasized. For these reasons, cutters have been developed for specific machine types and sizes, as well as for specific geological operating conditions. Different size cutters are required for different size machines. For example, while 483- and 508-mm (19- and 20-in.) cutters are used on large diameter TBMs, it is impossible to employ cutters so large on a small micro-TBM. Also, the cutter must be designed for the specific geological conditions under which it will be operating. The disc cutter rings required to bore extremely hard rock are the most expensive of cutter rings. However, they provide little advantage in weaker rock formations where less expensive rings will do the job as well. It is important to choose the correct cutter for the machine and the geological conditions in order to get the best balance of cost and risk.

Jan 1, 2009

By Q. Wu

Neural network methodology is used to predict mean particle size resulting from rock blast fragmentation. A blast data base developed in a previous study is used in the current study. A part of this blast data was used to train a single-hidden layer back propagation neural network model for each of the similarity groups obtained in the same previous study. Levenberg-Marquardt algorithm provided the most stable and efficient training out of the four algorithms evaluated. An extensive analysis was performed using a part of the blast data to estimate the optimum number of units for the hidden layer for each similarity group. The remaining blast data are used to validate the trained neural network models. Capability of the developed neural network models is determined by comparing predictions with measured values and predictions based on one of the most applied fragmentation prediction models appearing in the blasting literature. Prediction capability of the neural network models was found to be strong and better than the existing most applied model. Diversity of the blasts data used is one of the most important aspects of the developed models. The developed neural network models are suitable for practical use at mines.

Jan 1, 2011

By R. Benito

This paper describes the application of modern data-analysis tools, such as data mining, to determine a representative cost driver for haulage activity. This cost driver was subsequently used to trace incurred haul costs by bench for openpit optimization. For this purpose, large amount of previously unused cost and production data from an open pit mine was extracted, loaded, transformed and integrated into a data warehouse. Predictive modeling was performed using Microsoft Decision Trees algorithm to compute expected unit haul costs by bench for future mine expansions. Finally, a sensitivity analysis was carried out to determine the effect of two cost drivers (if any) for incremental haul costs in the final pit outline process.

Jan 1, 2008

By Geoffrey Fosbrook, Donald Phillips, Anil Parikh

The Second Avenue Subway is a $16.8 billion project planned by the Metropolitan Transportation Authority (MTA) in New York City. It will reduce overcrowding and delays on the Lexington Avenue Line, improving travel for both city and suburban commuters, and improving access to mass transit for residents of the East Side of Manhattan. The project is a new, two-track, 13.5 km (8.5 mile) subway extending from Lexington Avenue at 125th Street in Harlem on the north end of Manhattan, to Water Street at Hanover Square in Lower Manhattan. The first phase of construction includes rock tunnels from 92nd Street to 62nd Street and connection to the existing 63rd Street station, three new stations, and track and systems from 105th Street to 63rd Street, allowing service between 96th Street and Brooklyn via an existing Broadway Line. The following describes the Project in detail, discusses the construction challenges addressed in the design, and the initial design/build contract to be awarded in 2005. A discussion of the planned mined construction of two rock caverns and a cut-and-cover station construction are also included.

Jan 1, 2005

By Bruno Bussière, Guosheng Zhan, Michel Aubertin, Vincent Martin, Robert P. Chapuis

The study evaluates the hydrological behaviour of exposed and covered waste rock dumps. The objectives were to determine the major factors influencing unsaturated flow in waste rock dumps and covers, and to improve the in-situ, laboratory and numerical modeling characterization methods. Using material properties obtained from in-situ and laboratory tests, waste rock dumps of different configurations, with and without covers, were modeled. It was found that a properly designed “Store, divert and release” (SDR) cover allows most of the water to be diverted downslope and discharged outside of the waste rock dumps. The SDR cover seems to work efficiently even in extreme storm events. The numerical modeling results show that the unsaturated hydraulic properties (e.g. air entry value and water entry value) of the materials largely control the infiltration of water into waste rock dumps.

Jan 1, 2005

By K. N. Panigrahi

India bestowed with 6000km of the coastal belt, contains some of the richest and largest placer deposits with a mixture of heavy minerals like ilmenite, rutile, leucoxene, zircon, monazite, sillimanite and garnet. Each of the minerals is having economic value due to its inherent characteristics for industrial use in fields of paints, metallurgy, refractory, abrasive and so on. The reserves of titanium bearing minerals (ilmenite, leucoxene, and rutile) in the country is around 378 million tonnes. More than 90% of the titanium based minerals produced worldwide are utilised for making value added products in the pigment industries. Approximately 8 million tonnes of monazite reserves are available in the country from which several rare earth elements like cerium, neodymium, lanthanum, yttrium etc. can be extracted for use in several industries. The country contains a deposit of about 20 million tonnes of zircon, which is used in foundries, refractories, ceramics and chemicals. India has a reserve of 107 million tonnes of garnet and 131 million tonnes of sillimanite required for the abrasive and refractory industries respectively. Keeping in view the multifarious uses, the beach sand minerals are being exploited to have the economic growth of the nation. Although the process adopted for the separations are simple, the equipment involved are specially designed because of the nature of the material of construction. Starting from the spirals to magnetic separators, all equipments are manufactured outside India, which is not only costly, but the availability also takes much time for fulfilling the import formalities. Unlike open cast mining, beach sand mining is a environment friendly mining because dredging is implemented to cut and pump the loose sand through a slurry pump causing less damage to the surface topography as both mining and backfilling takes place simultaneously. Therefore all out efforts are made to explore the beach sand placer deposits in an economic manner to emerge as a leader in the global mineral industries.

Jan 1, 2005

By G. S. Takenaka

When Bridger Coal Company transformed their operations from surface mining to an underground longwall operation their plans included not only the addition of new mining equipment but also surface fans for a blowing (supply) air ventilation system. The original system concept included a propane gas fired air heater to preheat the intake air during cold weather and a dual parallel fan and duct system. One fan operated to ventilate the mine while the other fan was for stand-by emergency operation. Equipment proposals were submitted in March, 2005 based on the dual parallel fan system. Discussions conducted during the equipment selection process revealed that several alternative system design concepts were available. The alternative concepts included innovation features that not only saved space and cost but also reduced operating expense as well. Many of the features were incorporated into the final design of the system. A comparison of the original system concept and final installation design are presented in the paper in addition to details of the features and the derived benefits.

Jan 1, 2009

By Arthur Darby

The city of Kuala Lumpur was founded in 1857 by miners seeking tin near the confluence of the Klang and Gombak rivers. The rapid development of the city and surrounding area since independence has led to more rapid runoff during rainstorms and to gradual canalisation of the rivers with some restricted sections. The outcome has been more frequent and more severe floods (Abdullah 2006). At the same time the centre of Kuala Lumpur has become a modern inter-national city with tall office buildings, hotels, and shopping centres connected by a network of wide roads and commuter rail systems. With these the cost of dislocation during floods has risen as has the cost of making good damage afterwards. The Government of Malaysia considered these consequences unacceptable and sought ideas from the private sector for a solution. Potential solutions consisted of variations on the themes of bypassing the city centre with a flood relief tunnel or of providing off channel storage or a combination of both. Since under Malaysian law a tunnel cannot be constructed under private property unless this is first purchased or agreement reached with the owner, it was necessary for most of the tunnel alignment to run below existing heavily congested roads. After considering these facts Gamuda Berhad and MMC Berhad, two leading Malaysian development and construction companies, decided to propose to Government an innovative solution in which the tunnel would be used to carry road traffic except during floods.

Jan 1, 2008

By Keith Schaeffer

This paper presents a history of the planning, engineering and construction completed for the railroad tunnel crossing part of the West Elizabeth Avenue Storm Drainage Project, undertaken to relieve flooding within the West Elizabeth Avenue area in Linden, NJ. The Railroad Crossing Contract is part of the larger Linden Drainage Improvements Project consisting of a new gravity storm sewer system. The improvements are required to provide additional storm drainage for the City of Linden and the Merck Pharmaceuticals manufacturing facilities in the City of Linden.

Jan 1, 2008

By James A. Madonna

Information gathered while studying geological parameters that govern fine gold deposition in the a1luvial environment can be applied to the technological development and selection of fine gold recovery systems. It is recognized that substantial gold losses occur in the minus 1.5 mn (minus 12 mesh) fraction using conventional sluicing systems. Within the past two decades much attention has been given the design and efficiency of these thick bed concentrators. Studies and comparisons drew information from several foreign and domestic placer operations. These studies concentrated on: 1) the physical and chemical properties of alluvial gold 2) the parameters that control fine gold deposition 3) the geometrical form, components and general working structure of conventional sluicing systems 4) the physical properties which contribute to the overall efficiency of a sluice system 5) the comparison of three major styles of conventional sluicing systems. A dramatic improvement regarding fine gold recovery and water quality was observed when using modern multiple-channel sluicing systems in place of conventional single-channel sluicing systems.

Jan 1, 1988

By Dejan Petrović, Pavle Stojković, Jelena Ivaz, Saša Stojadinović

In spite of the fact that flyrock phenomenon represents the real threat for personnel and machinery, it still remains insufficiently investigated. There are efforts, in the mining community, to explain the causes of flyrock, but the models capable to accurately predict flyrock occurrence and define the flyrock distance still do not exist. This article is an attempt to establish such a predictive model. The model utilized the adaptive nature of artificial neural networks and combined it with the accuracy of numerical modeling of physical phenomena. Necessary data were collected by high-speed camera recordings of actual blasts at three different surface mines and processed for further use for artificial network training. The result was a neuro-numerical couple which was capable to predict flyrock occurrence, estimate the launch velocity of flyrock fragments, and calculate the maximum distance of flyrock fragments. The safe distance was then calculated by multiplying the flyrock distance with a factor of safety. The article explains the procedure for data acquisition and processing, artificial network construction, training, and validation. It also explains the principles of flyrock distance calculation and, finally, provides a definition of factor of safety and safe distance. The results showed that the prediction was satisfactorily accurate and reliable.

Oct 22, 2021

By J. C. Potvin

Although the occurrence of deposits of titanium minerals on Kenya’s present day beaches and adjacent dune systems has been well documented, the potential for older formations to host economically viable deposits had not been recognised until recently. The Magarini sands formation in Kenya has been found to contain deposits of ilmenite, rutile and zircon in quantities and grades that have the potential to be commercially exploited. Since 1995, Tiomin Resources Inc. has explored these deposits and has identified one deposit, the Kwale project, as being able to support the development of a mine producing some 300,000 tpa ilmenite, 75,000 tpa rutile and 37,000 tpa zircon. Tiomin plans to start production by late 2002. Construction of a US$137 million operation is set to commence in the first half of 2001.

Jan 1, 2001

By Peter Haller

Introduction The impact of the Comprehensive Environmental Response, Compensation, and Liability Act, or Superfund, as well as the Resource Conservation and Recovery Act (RCRA) and their state counterparts underscore the intention of the nation's lawmakers to reduce the risk from hazardous substance to American society. The promises and requirements embodied in these laws, together with their prospects for liability, will continue to have a very substantial impact on decision making in the mining industry. These laws present the prospects for staggering liabilities, often of an unquantifiable nature in terms of time and amount. It is therefore necessary to keep them in clear focus. This is particularly true in light of President Reagan's signing into law the Superfund amendments on Oct. 17, 1986, and in light of the Environmental Protection Agency's (EPA) major policy pronouncement of July 3, 1986, regarding solid wastes from extraction of ores and minerals. This article examines the general trends as well as the specific provisions of these laws in an effort to assess the prospects of liability for the mining industry of releases of hazardous substances into the environment. Hazardous substances vs. hazardous wastes The distinction between the terms "hazardous substances" and "hazardous wastes" is important to appreciate for the purposes of assessing the potential for liability for a mining operation. Hazardous substance is a term that appears in and is defined in the Superfund Act. In Superfund, it is defined by reference to other substances that have been declared to be hazardous under other federal environmental statutes, such as RCRA, the Clean Air Act, and the Clean Water Act. Hazardous waste is a term that is less all-encompassing than hazardous substance, as that term is defined by RCRA. Hazardous substances do not need to be wastes to be considered hazardous for the purpose of Superfund liability. A "release" of a hazardous substance into the environment can bring about potential liability under Superfund. Many mining wastes, even though they are not considered hazardous wastes by EPA under RCRA, have been determined by that agency to be capable of bringing about liability under Superfund if they contain chemical substances, such as the heavy metals copper, lead, mercury, zinc, silver, and others. Therefore, it is not sufficient for the mining industry to be able to answer whether one has hazardous waste at a mining site. That question only goes partway in addressing the potential for liability. The next question is, do one's solid or liquid mining wastes contain hazardous substances that could bring about liability under Superfund? Superfund 1980 law: A review Some provisions of Superfund as it existed before its recent amendments must be considered. The law provides that the owners and operators of mining sites, together with those who transport hazardous substances to such sites, can be held jointly and severally liable for the cost of cleaning up the site. The concept of joint and several liability means that one party, as among many, can be held totally responsible for the costs of cleanup. This is particularly true where the harm done by many parties to the envi-

Jan 2, 1987

By Lloyd M. English

During the past 30 years, the research arena has changed significantly in all fields, mining included. The relative representation of the topics of research, how the research is performed and who has performed the research have all changed. Although there are a lot of subjective ideas and anecdotal "analyses" concerning these changes, there has been no actual study of these trends to verify the facts. This study was divided into six five-¬year periods for the purposes of comparison. Some of the trends analyzed are co-authorship, research areas, research sponsors and cooperative efforts. In today's research arena, 30 years is a long time. Technology has advanced more rapidly than in any time previously and that pace continues to increase. There are more researchers, more tools for research and an increasing number of companies, agencies and institutions engaged in research. The pace of change and its impact is often discussed and debated at professional meetings and in institutions that engage in research. These conversations will often influence the research decisions of the participants in directions to take or subjects to pursue.

Jan 1, 1995

By Rong Lu, Hao Wu, Bing Dai, Guoyan Zhao, Li Cheng, Weizhang Liang

Affected by the disturbance of blasting activities, deformation instability and rock dynamic disasters are prone to occur in deep hard rock roadways. Thus, it is particularly necessary to understand the failure behavior of rocks and roadways under dynamic loads. In this study, a series of impact loading tests were carried out on sandstone samples with and without a circular cavity by a modified split Hopkinson pressure bar (SHPB) test system. The mechanical properties and energy evolution of the samples were systematically investigated, and the effect of cavity size was analyzed. The results showed that the presence of the cavity in the samples weakens the dynamic compressive strength by more than 10%, and the peak strain and brittleness are also reduced to varying degrees. Under dynamic loading, spalling cracks occur first on the roof and floor of the cavity, and then different numbers of shear cracks are formed on the sample diagonals. The eventual shear failure mode is the result of the connection of the shear cracks and the cavity. As the cavity radius increases, the dissipated energy density and fractal dimension both grow accordingly, leading to smaller and smaller rock fragments. The dynamic failure behavior of the circular cavity can be well explained based on the dynamic stress distribution law. Overall, this study can provide a reference for the study of the mechanism of rock burst in deep roadways.

Feb 18, 2021

By B. Anameric

The pig iron nugget process is gaining in importance as an alternative to the traditional blast furnace. Throughout the process, self-reducing?fluxing dried greenballs composed of iron ore concentrate, reducing-carburizing agent (coal), flux (limestone) and binder (bentonite) are heat-treated. During the heat treatment, dried greenballs are first transformed into direct reduced iron (DRI), then to transition direct reduced iron (TDRI) and finally to pig iron nuggets. The furnace temperature and/or residence time and the corresponding levels of carburization, reduction and metallization dictate these transformations. This study involved the determination of threshold furnace temperatures and residence times for completion of all of the transformation reactions and pig iron nugget production. The experiments involved the heat treatment of self-reducing?fluxing dried greenballs at various furnace temperatures and residence times. The products of these heat treatments were identified by utilizing optical microscopy, apparent density and microhardness measurements.

Jan 1, 2007

By M. Batzle

The upper Arkansas basin has some of the greatest potential for geothermal development in Colorado. Over several summers, students conducted an investigation using seismic, gravity, and magnetics in order to help identify the large structures and basin fill associated with the Rio Grande Rift. Adjacent to Mount Princeton Hot Springs, near surface geophysics was conducted to help understand the faulting and fractures that act as a conduit for hydrothermal flow. The methods used included high frequency 3D seismic, magnetics, gravity, D.C. resistivity, and self potential. Throughout the Mount Princeton area, passive seismic, vertical seismic profiling, and well logging were also used to better understand the geology and activity of the region. The results indicate for the area northwest of the hot springs, a 40 to 50 m thick unconsolidated layer overlying the fractured granitic basement. The DC profile shows a deep geothermal anomaly of low resistivity which correlates with a positive SP anomaly in the same region. In the Chalk Creek valley, a shear zone extends from the north east to the south west, just south of the Chalk Cliffs. There appears to be an upward migration of the water through this shear zone which then flows along the porous sediments towards the south in this area. The deep seismic data collected in the center of the basin suggests that the depth to the basement is approximately 2000m. Also identified on the deep seismic are two major faults on the west end and two minors at the east end of the cross-section. An alteration zone is identified between the faults and a possible Precambrian northeast trending shear zone. The potential for developing an Enhanced Geothermal System (EGS) near the center of the valley is high. Our geophysical results indicate a deep basin fill near the center of the basin providing high temperatures. The range front (Sawatch) fault is observed to penetrate under the center of the basin and is an attractive target for natural fractures.

Jan 1, 2011

By P. A. Plunkert, D. E. Morse, Pui-Kwan Tse, W. D. Menzie, Lucy McCartan, J. F. Papp

China’s burgeoning economy is responsible for a major share of recent world mineral consumption increases. In addition to factors traditionally recognized in market economies1 and factors unique to specific commodities, Chinese consumption now plays a major and increasingly important role in energy and mineral markets for many commodities, such as aluminum, copper, iron and steel, and oil. China has the world’s second largest economy after the United States. And its long-term importance to the minerals markets is even greater than indicated by its gross domestic product (GDP), which is currently less than two-thirds of that of the United States (Table 1). This is because China’s rising standard of living is accompanied by rapid industrialization and urbanization. Its consumption of mineral materials for infrastructure development for its very large population is significantly greater per capita than that of such developed economies as the United States, the European Union and Japan. In other words, China’s per capita production is rising at a rapid rate and will probably continue to do so for many years.

Jan 1, 2006

By J. F. Lupo

Leaching operations combine both metallurgical and hydraulic processes to extract metals from the ore heap. In the design of leaching operations, metallurgical tests and simple hydraulic tests are often conducted to define operational parameters such as leach cycle time, application rate, lift height, and effective leach area. While metallurgical constraints are often the primary focus on leach facility design, the hydraulic factors are also critical to the overall success of the operation. Some of the hydraulic factors that are known to impact solution flow through heaps include: • Ore physical and hydraulic properties, • Variation in ore properties under heap loading, • Ore mineralogy and its susceptibility to chemical and/or mechanical degradation, and • Heterogeneities within the heap. This paper presents a discussion on hydraulic factors that may impact the effectiveness of leaching operations. In addition, methods are presented which may be used to assess flow conditions within active and inactive heaps.

Jan 1, 2000