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By D. L. Kowal, P. J. Whittaker, M. A. Tuzun, N. O. Lotter

The area of flotation testing of drill-core is important in the business plan of most mining companies. Metallurgical information derived from this practice can be used to advantage in strategic decision-making. Sampling, flotation testing and subsequent Qem SCAN analysis of a mineral resource is one example of this approach. Anew resource, located in Sudbury, Ontario, is being assessed for the Sudbury Operations of Falconbridge Limited, which includes the Strathcona Mill. In this case, it was possible to improve the value of information from sampling and flotation testwork by using an improved, statistically-based test design, by sampling the resource by generic end-member ore type, and by integrating the Mineral Processing and Mineral Science disciplines into a Process Mineralogy team. In addition to producing standard metal grade and recovery information, this new approach provides more reproducible information from representative samples and flotation testing in a replicate format. Qem SCAN technology is used to produce a size by size mineral balance, including both modal percentages and liberation, from which flotation models for each ore type can be developed. As a result, a key understanding of the potential behaviour of a given ore type, if mined and then processed at the current mill operation, is gained at the 95%confidence level. The three ore types of this mineral resource were shown to have different flotation characteristics. Quantifying the mineralogy and liberation in each of the three ore types, has shown that this difference is due to changes in modal percentages of ferro-magnesium and magnesium silicate minerals such as pyroxene, talc and serpentine. Liberation across the three ore types is very similar and is therefore not responsible for variation in flotation performance.

Jan 1, 2003

By K. Kavouridis

On 30 April 2004, a large scale slope failure incident occurred at the external waste dump facility of the South Field Mine, in the Western Macedonia Lignite Center, Greece. This landslide involved the mobilization of waste overburden material (that was continuously deposited for the last 20 years) in the order of 40 Mm3, while the material that moved outside the boundaries of the waste dump was in the order of 3 Mm3. The factors that led to failure as well as the procedures and measures taken in order to stabilize the failure and resume normal operations at the South Field Mine are presented and discussed. Emphasis is given to the impact on mine operations and the cost related to resuming of normal production operation as well as to implementing important modifications and improvements of the materials handling system.

Jan 1, 2006

The selected list of sources of information on geology and mining in this section is provided to facilitate locating the major governmental and private entities in position to furnish such information, including societies and institutes; colleges, universities and technical schools; and magazines, yearbooks and mine directories, plus a number of general texts. In the case of publications, it should be noted that, in addition to those listed, most of the governmental and private organizations publish a wide variety of reports, bulletins, monographs, surveys and the like, including, in the case of governmental agencies, production statistics. The names of the mining schools and colleges in the following, with some exceptions, were taken from the International Handbook of Universities and & her Institutions of Higher Learning, and the Commonwealth Universities Yearbook, with the kind permission of the International Association of Universities, Paris, and the Association of Commonwealth Universities, London, owners of the copyrights. Abbreviations in the listings include the following: A. P., B. P, and C. P., Apartado Postal, Boite Postal and Caixa Postal (post office boxes); Br., Branch; and F., Faculty.

Jan 1, 1973

By R. B. Steele

The paper contains the results of the physical and mathematical simulations (based on the finite elements simulation) of the length and shape influence on the mechanical strength of the brex. Key words: Stiff extrusion, extruded briquettes, BREX, mechanical strength, cold strength, compressive strength, tensile splitting strength, oval shape, finite elements simulation. INTRODUCTION Extruded briquettes (BREX) exhibit a set of unique properties when compared with briquettes formed by alternative methods. Brex generally have sufficient integrity right after extrusion to withstand the necessary handling and stockpiling and does not require any special means and tools for the green briquettes strength conservation. In a typical die without an ancillary cutting device green brex tend to have very high length to diameter (L/D) or length to section area ratios. For round hole dies the brex are typically 5to 6 times the diameters and even longer. Stiff-extrusion allows also for the very easy changing of the forming dies. Dies with different cross-sectional shapes of the brex (round, ovals, square, hollow structures and many other two dimensional shapes) are possible, and common. The results of our investigations show how these geometrical shape factors contribute to overall quality of the brex both in terms of strength and as new charge components in metallurgical furnaces and processes [2-4]

Feb 27, 2013

By Jon Y. Kaneshiro, John S. Griffith, Anthony F. Stirbys, Mauricio Andrade

This paper presents an overview of the New Mississippi Tunnel Outfall for the Transportation Expansion Project (T-REX). The Outfall conveys highway and other urban drainage to the South Platte River as well as provides long needed relief from flooding problems in the southeastern portion of the Interstate 25 highway corridor. The Outfall tunnel incorporates a one-pass precast concrete segmented liner to convey storm water under I-25 then under Mississippi Avenue to the river. The Outfall crosses both the existing I-25 as well as the future improvements including under the Light Rail Transit, a new bridge abutment, widened lanes, and new retaining walls. The Outfall also crosses adjacent to several buildings and five bridges, under major traffic and utility intersections, and through difficult geology.

Jan 1, 2003

By Stephen C. Tadolini, Thomas M. Barczak

Western mines have had limited choices for standing support. Wood cribs were often too soft and unstable. The introduction of the Can support in the early 1990’s provided a very effective alternative and remains the dominant form of tailgate support. Water-filled prestressing cells are now used to cap the Can and preload it to provide an active roof load. The Cluster Prop, consisting of three timber wedge props bundled together, provides more capacity than an equivalent sized Can support and improves transport efficiency. However, the Cluster Prop is less stable and does not maintain a consistent load throughout its loading profile. Pumpable roof supports are another alternative support, but they have not been proven in high deformation environments. Alternative supports are also being used in longwall recovery operations. These include the Rocprop and Omni Prop, which are extendable support systems. They also provide active roof loading which can be beneficial in these applications. Specialty supports, such as the Sand Prop and Spider Prop, have also been introduced into western longwall operations. This paper compares the performance characteristics of these various support systems.

Jan 1, 2005

By T. Negeri, A. O. Orumwense

Microwave pretreatment is one of the emerging technologies which have been reported as having potential economic benefits for the processing of amenable ores. The application of microwave pretreatment to the processing of refractory and finely disseminated ores is of great interest as the technology can potentially reduce high comminution costs and improve mineral liberation. Sized ore samples were subjected to microwave irradiation at power levels varying from 1 to 5 kW over exposure times of between 1 and 6minutes in order to determine the influence of heating rate on mineral transformation, ground product size distribution and mineral liberation. The microwave irradiated samples were ground and subsequently floated. A comparison is made with non-microwave treated samples. Flotation grade and recovery show a strong dependence on the microwave absorption characteristics of the mineral components of the ore, in the following decreasing order -sphalerite, galena, and lastly chalcopyrite.

Jan 1, 2003

By T. Winkler, J. Tokarczyk, D. Michalak, W. Chuchnowski, M. Dudek

Engineering Methods aiding Sustainable Development of Mining Systems will be presented, and especially: virtual prototyping for designing of Mining Systems with Health Protection and Safety criteria taken into consideration, modelling and assessment of technical and health hazards that can occur during operation of Mining Systems, creation of knowledge repositories that disseminate safe work methods with consideration of existing language and culture barriers, dissemination of the methods integrating world community and Mining Systems users.

Jan 1, 2011

By Dean S. Rogers, R. A. Metz

The conventional role or exploration, development and grade control is examined in this paper within the context of the many and varied types of gold occurrences which are found at the Dome Mine. The account endeavours to trace the development of the total ore evaluation process, from diamond drilling through the exploration and drifting stage, to the stope development and planning phase of the operation, with an emphasis on sampling techniques and assaying procedure. The concept of ore reserve calculations is developed and the practice of grade control is described. In summary, the role of the geological, the engineering and the mining department is presented in relation to the contribution each has to make in the evaluation and exploitation of ore from one of the world's classic Archean gold deposits.

Jan 1, 1992

By Martin G. Taube, Dwayne A. Lewis

Drainage improvements at O’Hare International Airport, Chicago, IL included the installation of a drainage and storm water system to control the over?ow from nearby Willow Higgins Creek. This involved construction of a weir structure at the creek and the channeling of water from the weir to a newly constructed reservoir via three, 3.7-m(12-ft) diameter, underground storm sewer lines. The sewer lines passed beneath an existing, 2.3-m (90-inch) diameter high-pressure water main, which was to remain in service throughout sewer line installation. The soil composition around the water main ranged from medium stiff clays to silty sands and sandy silts. Triple-fluid jet grouting was used to stabilize the variable soil profile beneath the water main in preparation for tunneling and installation of the sewer lines. The varying soil strata presented a challenge to the project team to establish a constant set of jet grouting parameters throughout the stabilized zone while keeping within the specified unconfined compressive strength range for the stabilized zone of 690 to 1,380 kPa (100 to 200 psi)at 28 days.

Jan 1, 2003

By K. F. Unrug

Fractures of sedimentary rocks in the vicinity of the outcrop are commonly encountered around the world. Mine highwalls and numerous highway cuts give excellent views for detailed study of surface fractures. This paper gives an explanation of the origin of fractures as well as characterization of the distribution and extent of joint system with reference to lithologic composition of the rocks. Practical implications of the joint system affecting mine operations are described. Among the subjects discussed are: discontinuous deformation as an effect of surface subsidence, stability of mine portals and near outcrop underground operations, and stability of highwalls, when using highwall miners and strip operations. Some design procedures are recommended that can minimize the problems encountered in mining areas with intense joint systems.

Jan 1, 1994

By A J. Jonaitis

The DENVER Tube Press is a simple, high pressure (1500 PSI (100 bar» filtration unit, developed for processing difficult-to-dewater materials and to produce a handleable filter cake and clear filtrate product. Lab and pilot testwork conducted in Australia on coal fines (55-70\ -35 micron (400 mesh)) have shown that total moisture contents of less than 20\ are consistently achieved in the final cake products from the Tube Press. Currently, these coal super fines are sent to waste due to uneconomical mechanical dewatering methods, which were only able to reduce total moisture levels in excess of 30%. Calculated, throughput rates for the 500 Series Tube Press exceeded 1700 kg/hr (3750 lbs/hr). Feed solids concentration requirements are between 45 and 50\ to achieve these results.

Jan 1, 1993

By Holger Witthaus

Various seam conditions had been examined during longwall production at RAG German hard coal mines. Based on the field data a prediction method was developed considering separation planes as influencing factors for roof falls at the face. The characteristics, orientation, and density of separation are important factors on the occurrence of roof falls. In addition to geological influences, the performance parameters and geometry of support must be considered and optimized for the prediction and prevention of roof falls in a longwall face. Based on detailed macro- and microscopic investigations of e coal seams considering various ranks of carbonization, the origin and characteristics of separation planes are determined and a strata-specific influence on roof fall is interpreted. It was assessed that the coal face fracturing and displacement caused by the stress depend on the floor and roof strata conditions due to activation of the existing separation planes. Field studies are shown giving an idea of influences by advance rates of the longwall face, support delay and hydraulic pressure to the roof control in longwall faces in depth of more than 3000 ft. The analysis includes the application of specific software developed for longwall roof fall prediction as a result of a European research project. The software allows a laminar graphic display of roof fall probability, which is used for recognition of risk areas and risk management.

Jan 1, 2009

I reached New York at the start of my second South American adventure on Jan. 9, 1916. In the Anaconda office I found that we were not to take the steamer for two weeks which gave me time to study reports on Potrerillos and Corocoro. Reno Sales, whom I had met in Butte only casually, was to go with us to South America. Though he was only a little older than I, he was already an unquestioned leader of our profession, and we became and remained good friends. William Braden was in New York and would return to Santiago with us. Tom Hamilton would also be returning from a vacation. Leighton Stewart, a young engineer who was to work for Braden, was going on the steamer with us, taking along his wife. And of course Dr. Ricketts would go along. He had just become engaged to John Greenway's half sister, Kate Greenway, and in order not to be away from her longer than was necessary, he did not reach New York until a day before we sailed. This made eight of us who would be in the party. We were to go to Corocoro first, as Braden had taken an option on the Chilean company there. Development was already under way. As reports came in by mail we tried to get as good an idea of the property as we could before the actual examination. Mr. Thayer "put us up" at India House, one of the best lunch clubs in New York, and Reno and I ate our lunches there almost every day. Thayer, Braden, and Cornelius Kelley, who was to succeed Mr. Ryan as president of Anaconda, joined us when they could. At the lunches they told us about the under- ground war in Butte a few years earlier. When I wrote my chapter on the Butte wars in Romantic Copper more than 15 years later I could not help being biased a bit by my friends, all of whom were on the Anaconda side. But their opponents in the Clark and Heinze camp were just as biased in their comments on my book.

Jan 1, 1976

By James R. Dunn

The nature of water and clay in carbonate rocks is currently being investigated at Rensselaer Polytechnic Institute by various thermal and sorption techniques. Two basic concepts 'led to the present research. (1) To explain the expansion and contraction on wetting and drying of some unsound argillaceous carbonate rocks, it was postulated that the pore space around each clay particle is such that when water is sorbed by the clay, force is exerted against the pore walls. (2) The clays in expansive rocks are rejected from the growing dolomite crystals during their growth, and form a more or less connected network, thereby becoming "wettable," or available to water. New quantitative cold differential-thermal-analysis (electrocalorimetric) equipment was designed and constructed to check the "limited space" and "wettable clay" concepts and to determine the thermal nature of the transition of water to ice in rocks. This DTA equipment can detect the release of heat in freezing of less than 0.001 per cent water in a rock. Twenty-three rock cores (nine sound and fourteen unsound) and 4 procelain cylinders for standards were studied. In the nine sound rocks and in all the procelain cylinders, the rapid freezing of from 50 to 100 per cent of the water was readily detectable after 7 to 10° C of supercooling. No further freezing could be detected to -20° C. However, in eleven of the fourteen unsound rocks, no freezing was detected to as low as -40° C; in the other three, less than 50 per cent of the water froze. As a check of the DTA measurements, adsorption isotherms were determined for all materials. Calculations of theoretical freezing points for sorbed water again demonstrated that the least sound rocks had the most nonfreezable water. "Frost" sensitivity in these carbonate rocks is, therefore, probably not the result of the force of expansion of water to ice. The disruptive force is believed to result from expansion of sorbed, ordered water on clay surfaces. The relationship between the unfilled rock pores after 24-hour water saturation and the water sorbed at 85 per cent humidity at 30° C (i.e., the theoretical nonfreezable water delineates the sound and unsound carbonate rocks.

Jan 1, 1966

By Jessica M. Wempen, Dallan J. Coons, Bailey S. Simmons, Michael K. McCarter

Gate-road yield pillars are subject to increases in stress as the longwall face advances toward the pillars. Increases in pillar stress can be inferred by measuring roof/floor convergence surrounding the pillar. This paper presents a case study of convergence measurements surrounding a two-entry gate-road yield pillar in the head gate of a coal mine. Convergence was measured over a six-month period, as the longwall face approached and passed the pillar. Measurements were collected at eight locations surrounding the pillar: four locations in the travelway and four locations in the beltway. In addition to convergence stations, the pillar was instrumented with an array of seismometers. In future analysis, convergence measurements will be compared to seismic interpretations. This study reports on the geology and geometry of the longwall panel, the roof and rib support, the change in convergence over time, and the physical properties of coal and parting. Additionally, the convergence measurements are compared to pillar safety factor distributions derived from a finite element model. The convergence measurements contribute to the knowledge of when yield pillar abutment loading, caused by the encroaching longwall, is first detected. Knowing when abutment loading begins to yield the pillars can help define when standing secondary roof supports are required for head gate entry support.

By M. T. Worley

Joint Development Associates International, Inc. (JDA) began humanitarian relief and community development in Central Asia in1992, following the collapse of the former Soviet Union. Appropriate technology has played an important role in their efforts to assist those segments of society that are most vulnerable to poverty and disease. Three case histories are described to illustrate the successful implementation of simple, but effective technology in community development.

Jan 1, 2004

By V. E. Gall, A. Vonthron, J. Ninic, A. Marwan, M. König, G. Meschke, A. Alsahly

"In current tunneling practice, finite element simulations have become an integral element of the planning and design process. These models are most often manually generated using 2D CAD drawings, which is a laborious and time consuming process. In this paper, we propose a BIM based approach, in which the 3D FE-model is automatically generated through a set of compatible geometries of individual components, i.e. the geology, alignment, lining and the TBM. The BIM model also includes all relevant model parameters of the tunneling project that can then be incorporated into subsequent analysis to be performed during the tunnel drive. The setup and the execution of the FE-analysis are performed automatically utilizing all required data from BIM. The applicability and efficiency of the proposed strategies is demonstrated by means of project data from the Wehrhahn-line metro project in Düsseldorf, Germany. Both the design as well as the construction stage is considered. INTRODUCTIONIt is recommend to employ Finite Element (FE) simulations in order to ensure a high degree of safety and quality for any given project (Guglielmetti et al. 2012). As such, FE models form an integral part in the design and planning stages of modern tunneling projects. These models are often time consuming to construct and require data from many different sources. This data is most often not centrally stored and therefore not easily accessible. Additionally, the formats in which project data are stored are typically not compatible with the formats required by an FE program. This is especially true in the case of geometrical data, such as CAD drawings. Although existing design drawings are most often used as the basis for a FE model, a direct import into a FE program is most often not successful as the imported data generates a geometry that does not fulfill the requirements of a FEM model, such as model connectivity. Even if a geometry is successfully imported, other necessary aspects of an FE model, such as boundary conditions and material properties, must be applied manually. These incompatibilities inevitably result in the creation of a new model, which, especially in the case of complex 3D models, is a time consuming process."

Jan 1, 2016

By Mohammad Ranjbar Hamghavandi, Mohammad Ranjbar, Zahra Manafi, Mohammad Hassan Fazaelipoor, Mahin Schaffie

The present study introduces a new approach to understand the copper dissolution rate and to find an adapted mathematical statement for particle shrinkage rate in a batch bioleaching system. Four size classes of a chalcopyrite concentrate, namely [D1 : (−54 + 44)μm, D2 : (−44 + 38)μm, D3 : (−38 + 25)μm and D4 : (−25)μm], were used in the batch bioleaching tests by applying a mixed culture of moderately thermophilic microorganisms. The pulp density and temperature were 8 (%w/v) and 50 °C, respectively. Findings delineated that the bioleaching time can be divided into two specific time intervals: first, the surface reactions were the prevailing controlling step; second, the prevailing mechanism was diffusion through the product layer, whereas the overall rate of the process may be related to both through a Q factor using a mixed model. A mathematical model was developed based on particle size distribution (PSD) and a kinetic model. Experimental validation of the mixed model was accomplished by the representative sample with d80 = 54 microns. Results showed that the PSD of the specific sample was in good agreement with Rosin–Rammler function. Besides, the simulation result of the conversion fraction had the best conformity with the experimental data (with a maximum error of approximately 7%). This paper should be considered as an initial part of a larger, global model for chalcopyrite concentrate bioleaching.

By Hamid Maleki

A geotechnical monitoring program has been implemented at Energy West Mining Company for enhancing site-specific evaluation of longwall stress conditions. This program consists of underground measurements at five locations in two neighboring mining districts located in the Hiawatha and Blind Canyon Coal Seams under moderate to deep cover. Within the last five years, additional measurements, including data on recorded seismic events and face conditions, have been incorporated into the data collection program together with detailed geologic mapping of longwall gateroads. In conjunction with the measurement program, the authors have completed detailed boundary-element stress analyses of the mine plans. Models have been calibrated using the data from in-mine instrumentations and then routinely used for evaluation of mine plans at depths approaching 2,600-ft. The work has improved our understanding of load transfer, seismicity and yield pillar performance. It has identified areas of potential increased stress levels at certain longwall face positions and provided guidance to measures that could be considered to mitigate the potential for these increased stress levels.

Jan 1, 2009