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By Dominique Vié

Standards methods covers the procedures for testing deep foundation to determine the force and velocity response to an impact of a pile driving hammer or similar device. The results of analysis generally include an assessment of pile integrity and the value of maximum dynamic stresses. But evaluation of static bearing capacity remains a matter of individual engineering judgment. A new 1D finite elements model has been developed for dynamic stresses and velocity analysis. Following an international benchmark of bearing capacity prediction organised by the Belgium Building Research Institute (BBRI), 12 piles in a site of fissured stiff tertiary clay tested in 1999, and 12 piles in a site of dense sand tested in 2001, comparison are proposed between analysis of dynamic tests and static tests results. A procedure is proposed to take in account the results of dynamic test for evaluation of bearing capacity.

Jan 1, 2002

By R. W. Carn, D. Vincent

Environmental Considerations With significant increases in bulk coal movements through terminals, operators are under constant social and political pressure to reduce or remove environmental pollution problems incidental to their operations. To meet these requirements, both equipment manufacturers and terminal designers are endeavoring to design equipment and systems with stringent environmental controls. The most challenging environmental problems facing coal terminal designers and developers are terminal siting restrictions, dust control, and noise abatement. Terminal Siting Finding a suitable site can be a difficult problem because of public concern over coal dust or the impact of a terminal on the surrounding community or natural habitat of the area. Often the only suitable flat land available for terminal development is on a tidal estuary or salt water marsh with great environmental value. In many cases a period of four to six years of full environmental and social assessment has been needed. A recent example of such difficulties is the expansion at Roberts Bank, British Columbia, where environmental impact assessment studies and their public review took almost six years from initial expansion applications until the time of approval. Dust Control Modern coal terminal dust control techniques usually consist of water sprays at strategic locations to suppress dust. The application points include rail car or barge dumper, main conveyor transfers, perimeter sprays around stockpiles, stacker/reclaimer, ship-loader transfers, and loading spout. The water sprays may include a chemical wetting agent or surfactant to reduce the water requirement and increase effectiveness. Recently there have been advances with development of effective micro foam agglomerating agents. In these systems, a micro foam with very small bubble sizes is sprayed into the coal stream. The foam fills the interstices between coal particles and wets the coal fines. These systems have proven to be very effective and usually one application before stockpiling and one upon reclaiming will markedly reduce the coal dusting. Stockpile perimeter sprays can be operated either manually or at the sophisticated terminal, actuated by a computerized control system that senses key environmental conditions such as humidity, precipitation, and wind velocity. Most modern terminals collect the drainage from the stockpile area, remove the solids in settling basins, then recirculate the water to reduce water requirements and effluents from the site. Dusting of long-term storage stockpiles can be reduced by spraying the piles with chemical resin or latex binding compounds to seal the surface. These compounds also can minimize erosion of the pile by rainfall. Dust collection with air evacuation systems and cyclone or wet scrubbers can be used at key areas such as rail car dumpers, main conveyor transfers, and ship-loader spouts. The trend in dust control is away from dust collection since most dust collectors are high maintenance items requiring good operator supervision and servicing. Coal handling conveyors are usually open and uncovered. However, in areas requiring special attention they may be covered or even completely enclosed. Dust generation from terminal roads is often a significant amount of the total dust emitted from a terminal. To reduce this dusting, roadways where traffic is heavy can be paved or sprayed by water trucks. Speed limits can be enforced and use of tracked mobile equipment for stockpile handling rather than rubber-tired loaders is encouraged by authorities. Noise Abatement Terminals located close to residential areas are often faced with noise control problems. Noise can be one of the most difficult environmental problems to solve. Usually, use of electrically-powered equipment is encouraged to reduce noise levels. Rail car dumper houses can be totally enclosed to reduce both dust and noise emissions. Diesel locomotives can be fitted with special muffling devices. Green belts of trees surrounding a terminal or the ap-

Jan 7, 1983

By P Meehan, R McAree, Z Guan

Equipment maintenance is 30 - 50 per cent of the operating costs for a typical mining company. While this is substantial, its importance is beyond its significance as a cost heading. Modern mining requires large amounts of investment in capital infrastructure and equipment to produce a product sold at a low unit cost. To stay competitive, such a business has to focus on full realisation of its capital investment, ie sustained production at high levels. Maintenance plays an essential role in achieving this goal. Mining companies typically use a mix of breakdown or corrective maintenance, planned maintenance, and some condition-based maintenance. The share of breakdown maintenance has been coming down through more effective planned maintenance and better condition monitoring tools. Planned or preventive maintenance (PM) is playing an increasingly important role in todayÆs mining maintenance. This is the suite of inspection and repair/replacement actions performed at scheduled time intervals as part of a preplanned activity. The activities are scheduled well in advance and, usually, the current wear-state of the machine is irrelevant. For example, the replacement of a major gear may have been planned 18 months in advance; replacement is carried out when the time comes regardless of the actual condition of the gear. The PM costs are significant and include direct cost of parts and labour as well as the opportunity cost of lost production while the machine is under maintenance. It is important to identify the optimum PM effort because over-maintenance should be avoided as much as under-maintenance. A new concept called severity-based maintenance is introduced in this paper. We have seen that measuring equipment ageing in mining merely by counting the engine hours is a very imprecise way of planning and scheduling maintenance because the damage accumulated in one hour varies enormously from operator to operator and with changing pit conditions. We recommend continuous monitoring of duty on all major equipment. This is feasible without having to fit out the machine with an army of sensors because most of the physical sensors required by dutymeters are already installed and maintained as part of the existing performance monitors. While the investment is modest, the potential benefits are huge and can be grouped under three headings:Immediate benefits will come from providing operators with direct feedback on the effect of their behaviour on machine health and training them to use this feedback to correct their operating style. The equipment can operate closer to the limits of capacity, producing more without unduly sacrificing the availability by monitoring and controlling the severity of the operation, ie the duty on the machine. Longer term benefits accrue from establishing correlations between actual time to failure data and measured equipment duty and using these correlations to optimise maintenance effort as well as planning new equipment purchases and warranty conditions.

Jan 1, 2002

By Jai-Woon Moon, Wonnyon Kim

Deep-sea hydrothermal vents (hereafter chimneys) are commonly found on the new crust forming along divergent plate boundaries. Related to the chimney cycle from birth to death, it is hard to define the growth stage of the chimney due to a brief life span of the venting hydrothermal plume. Here we try to categorize the mineral magnetic properties of the chimneys according to their venting fluid-temperatures. Hydrothermal sulfide deposits in the Southwest Pacific were explored in 2012 and chimneys were collected using remotely operated vehicle (ROV) and Grab with AV camera (GTV). In the present study, mineral magnetic properties of three Cu-rich chimneys were measured: a high-temperature chimney showing a venting fluid-temperature of about 200°C (ROV01); a lowtemperature chimney of about 80°C (GTV01); and an inactive chimney (ROV02). The chimneys were sliced to ~1 cm intervals from core to outer margin. Magnetic properties of ROV01 are dominated by pyrrhotite, except for the most outer part that experienced severe oxidation. Concentration and grain-size of pyrrhotite are relatively low and fine respectively. In the GTV01, pyrrhotite, dominant in the core, is gradually mixed with hematite toward the outer margin of the chimney due to secondary oxidation. Both the concentration and grain-size of the magnetic minerals are greater compared to the GTV01. High concentration and large grain-size of magnetic minerals characterize ROV02. Dominant magnetic phases are pyrrhotite, hematite, and goethite. In particular, the most outer margin shows the presence of magnetite produced possibly by magnetotactic bacterial activity. Such distinctive contrast in magnetic concentration, grain-size, and mineralogy among three different types of chimneys enables the life stage of the Cu-rich chimneys to be determined through a mineral magnetic study.

Sep 1, 2014

By Donald Leroux, Dave Scott, Giovanni Di Prisco

"The Lady Loretta lead-zinc deposit in Northwest Queensland, Australia contains an average of 5.9% lead, 17.1% zinc and 97 g/t silver. Ore mineralization is mostly comprised of fairly complex intergrowths of pyrite, sphalerite and galena. Starting in 1998, Noranda Inc., the major joint venture partner of the project, conducted extensive metallurgical test work, which culminated in July - August 2000 in a series of Pilot Plant tests. A common thread to all the metallurgical work has been the deportment of a large portion of silver into non-payable metallurgical products. Average silver distribution from four Pilot Plants shows a distribution of silver in lead concentrate of 28%, whereas silver in zinc concentrate was 49%, and 23% in the final tails.The consistently poor silver recovery as well as the fairly unusual silver distribution, particularly in zinc concentrate, was considered an issue to be thoroughly investigated. A mineralogical plan was devised to determine if these particular metallurgical results were somewhat related to the nature and mode of occurrence of silver carriers. Work was performed to determine discrete silver-bearing minerals and/or silver contained in solid solution in a suite of commonly occurring sulphides. Ore microscopy, SEM methods, Electron Microprobe and Ion Microprobe analyses were all used to answer these questions, and to find the silver carriers, so a metallurgical plan could be devised to improve silver recovery.INTRODUCTIONPotential economic exploitation of the Lady Loretta deposit in Queensland, Australia is driven by revenue derived from zinc and lead flotation concentrates and co-product silver recovery in lead. Relatively low recoveries of payable silver to lead concentrate, and high silver distribution to zinc concentrate necessitated an investigation into the natu"

Jan 1, 2002

We present a novel hybrid algorithm for quantifying the ore grade variability that has central importance in ore reserve estimation. The proposed algorithm has three stages: (1) fuzzy clustering, (2) similarity measure, and (3) grade estimation. The method first considers data clustering, and then uses the clustering information for quantifying the ore grades by means of a cumulative point semimadogram function. The method provides a measure of similarity and gives an indication of the regional heterogeneity. In addition, grade estimations can be obtained at different levels of similarity using a weighting function, which is the standard regional dependence function (SRDF). Keywords: Grade, fuzzy clustering, similarity measure, point madogram, weighting function.

Jan 1, 2008

By G. G. Goble

Significant progress has been made in the past decade in determining the load bearing capacity of pile foundations. Developments in the means of prediction of pile capacity as limited by soil strength have been substantial, particularly in the use of dynamic methods. The use of currently available equipment, analytical procedures, and practices in the field, will often produce material economies on a job by allowing increased loads with proven factors of safety. This approach justifies the minimum number of piles required for a safe foundation in a wide range of job sizes and soil conditions. To avoid exposing the reader to excessive detail in the body of this paper, technical topics have been covered more thoroughly in several appendices. I. Wave Equation Analysis of Piles Appendix A II. Dynamic Monitoring and the Pile Driving Analyzer Appendix B III. Case Method Capacity Calculation Appendix C IV. Case Pile Wave Analysis Program Appendix D 1 Preliminary Analysis In designing driven pile foundations, there must be a close relationship between design, construction control procedures, driving practices, and the size of the job. Small commercial buildings or residences involving loads that are only a fraction of the pile capacities do not justify the expense of detailed design processes or elaborate construction controls. Nevertheless, some preliminary analysis of the job requirements and a limited subsurface investigation must be made to understand existing conditions and the possible foundation solutions. In other words, it is necessary to determine that driven piling is the best overall choice of foundation.

Jan 1, 1988

By J. A. Botín

Traditional risk quantification methods provide little information on the sources of risk, and tend to produce static over-conservative evaluations, which do not account for changes in the performance of the project. Capital investment decisions for large mining projects require of more complex risk evaluation models, that include the value of flexibility and the different risk levels associated with uncertainty on project variables (price, grade, dilution, production rates, among many other). In this context, Real Option Valuation (ROV) methods have proven potential to quantify the risk associated with such variables and integrate alternative scenarios and management strategies into the evaluation process. In this paper, a risk quantification model is developed, which successfully quantifies the risk associated to dilution, as a function of production rate. This model is then validated in a case study on the Chuquicamata Underground Mining Project.

Feb 27, 2013

This method determines tellurium at concentrations down to 0·01 p.p.m., with geochemical accuracy. Tellurium is volatilized from the rock at 800°C in the presence of sulphur from decomposing pyrite, condensed, dissolved, and finally determined by atomic absorption in a long tube burner. The distribution of Te is shown near some gold lodes at Kalgoorlie. Lastly, a method of synthesizing Te-free pyrite from sulphur and ferrous sulphate is described.

Jan 1, 1969

By Luis Haro

Puesto que el deslizamiento de relaves constituye uno de los principales riesgos para la vida y seguridad de los embalses, se desarrolló un programa que rehabilite los depósitos de los relaves a través de los gaviones y geomallas como elementos que estabilizan los relaves descargados. En este sentido, el uso de geosintéticos revolucionó el diseño de los relaves y sistema productivos y permitió un mejor manejo ambiental de los relaves. Asimismo, la utilización de gaviones como paramento externo en el sistema suelo armado, otorga mayor rigidez al mismo en el caso de paredes, taludes más verticales, drenaje y protección contra la erosión. En consecuencia, el uso de gaviones y geomallas es aplicable para la construcción de depósitos de relave y estabilización de depósitos inactivos.

Sep 13, 2001

By Dawn C. Tattle

[ ] Panoramic View of Completed Facade Supports The following case history describes the installation of earth retention systems, historical facade supports and structural caissons by Anchor Shoring & Caissons Ltd. at the Air Canada Centre/Raptors Stadium Project in Toronto, Ontario, Canada. The Air Canada Centre/Raptors Stadium project includes a 140,000 square foot office tower, a 20,000 seat basketball arena and their support facilities. The arena within the complex will also have the ability to host hockey, ice shows, concerts and family events.

Jan 1, 1997

By Yajie Wang

High horizontal stress and its adverse effects on longwall gate entries have been witnessed in many US coal mines for the past years. It can cause cutter roofs and leads to roof falls either in the headgate or tailgate entries depending on the relative orientation of the panel to the maximum principal horizontal stress. Underground observations have shown that if the maximum principal horizontal stress is perpendicular to the panel entries, the roof is in the worst condition and if the maximum principal horizontal stress is parallel to the entries, the entry is in the best condition. However, little has been done about the high horizontal stress effects on panel entries subject to different orientations of high horizontal stress. In order to design a longwall panel and control the roof effectively, the redistribution and concentration of high horizontal stress field must be fully understood. Using 3-D finite element analysis, this paper presents the high horizontal stress redistribution and concentration for a retreat longwall face with different orientations of high horizontal stress. Based on the results, possible roof failures for different orientations of high horizontal stress are analyzed. A panel design criterion is recommended.

Jan 1, 1996

By Changqing Su

A batch incubation experiment has been carried out to investigate the optimal condition for the microbial remediation of hexavalent chromium (Cr(VI)) in soils contaminated by chromate ore processing residue at Hunan Iron-Alloy Factory in China. The optimal condition was obtained by comparing the remediation efficiency of Cr (VI) by indigenous bacteria under different culture media, the quantity of nutrient sources, the pH and the temperature. The results indicated that glucose and yeast extract was the optimal component of culture medium and the quantities of the above components were 8 g L-1 and 13 g L-1, respectively. The optimal temperature and pH value were 30_ and 10.0, respectively. A bioreactor was operated under the optimal condition to evaluate the efficiency of Cr(VI) remediation in the contaminated soil. The result showed that water soluble Cr(VI) in soils was reduced from 320 mg kg-1 Cr(VI) of the initial concentration to below detection limit after 30 h in a bioreactor. Thus, there is a large potential to make bioremediation for the reduction of Cr(VI) to Cr(III) by the addition of optimal culture medium under aerobic condition.

Jan 1, 2010

By D. E. Pollock

Recent NIOSH published information has shown an increase of rapidly progressive coal workers? pneumoconiosis (CWP) in the southern Appalachian coal region (SAR) of the U.S., despite the fact that compliance data indicates that most coal miners have been exposed to coal mine dust concentrations below the statutory limit of 2.0 mg/m³. While the exact cause of these elevated CWP levels in the SAR has not been established, several factors may be contributing to the increase in occupational lung disease among coal miners. The mining of high rank coal is known to lead to higher CWP rates, and this type of coal is mined in a portion of this region. Also, a high percentage of the mines in the region are on reduced dust standards because of the high silica content of the airborne dust resulting in miners possibly being exposed to excessive amounts of respirable silica dust. Exposure to excessive amounts of respirable silica dust can lead to silicosis, a disabling and potentially fatal lung disease. NIOSH's Respiratory Hazards Control Branch has been investigating the possible causes that would account for the observed higher trends in disease progression through literature review, data analysis, and in-mine surveying. The investigation to date has revealed that underground mines are faced with cutting large amounts of rock in order to maintain haulage clearances. Cutting rock not only increases the potential for silica exposure, it increases the requirement for machine maintenance which was a concern observed during dust surveys conducted by NIOSH. Over half of the mines operating in the SAR are on reduced standards due to high silica content. Adequate face ventilation of the continuous miner and roof bolter and limited down-wind operations from the miner are also issues of concern and items which require the constant attention of miners operating in these conditions. Disclaimer: Mention of any company or product does not constitute endorsement by the National Institute for Occupational Safety and Health.

Jan 1, 2009

By W. M. Deaton

[The formation of gas hydrates in natural-gas pipe lines depends on temperature and pressure conditions in the lines as well as on the presence of condensed water. The operating pressure in a pipe line may be determined easily and usually is available from the records of operation, but the temperature seldom is known. In cooperation with the American Gas Association, the Bureau of Mines, in its investigation of gas hydrates, conducted a pipe-line-temperature survey and studied underground temperatures at depths at which pipe lines ordinarily are buried and the relationship of these temperatures to prevailing atmospheric conditions. A similar but more limited study of this type was, conducted by engineers of the Bureau of Mines a number of years ago.4/A summary of the earlier findings was included in a general report by the Bureau on the flow of natural gas through high-pressure transmission lines.5/ In the present study, data on temperature variations were obtained at several places widely separated geographically. This information should assist pipe-line engineers in designing and operating natural-gas pipe lines. In the pipe-line-temperature survey here resorted, a study was made along a 22-inch natural-gas pipe line: originating near Amarillo, Tex., and extending northwestward through New Mexico into Colorado (fig. 1). Some data also were collected along a 16-inch line extending southward from Amarillo. In the study of underground temperatures and their variation with atmospheric temperature, recording; equipment was installed at the]

Jan 1, 1941

The development and introduction of a preventive maintenance scheme in the coke ovens department, coal preparation section, of The Broken Hill Proprietary Co. Ltd., Newcastle steelworks, is described together with its operation and the results achieved during the first 12 months.'fhe scheme consists essentially of an engineering analysis of the plant to establish maintenance schedules, and to record the details on reference cards.Items are reviewed progressively and a weekly work schedule is prepared, from which work orders are passed on to the maintenance foremen. These foremen in turn originate action orders and issue inspection sheets as required. Results are then reported back to the maintenance planner and used to revise norms, practices, and cycles.INTRODUCTIONWhat is maintenance? Some people consider maintenance to be the work involved in putting things together again after they have fallen apart. The author regards it as the mechanical care and repair of plant machinery and equipment to keep it operating in sound mechanical condition, without undue interference with production processes.Maintenance may be organized or haphazard, and, too often, what has been fondly imagined to be nicely controlled and organized maintenance proves, under pressure, to be more correctly described as haphazard. Haphazard maintenance deals with breakdowns as they occur, and frequently finds itself confronted with more breakdowns than can be handled. Even organized maintenance, if not based on sound planning, can, at times, be found in a chaotic state, because of unexpected and unanticipated breakdown.Properly planned and scheduled maintenance permits an orderly and controlled approach to the problem of maintain...

Jan 1, 1961

On July 1, 1969, the Explosives Research Center merged with the Health and Safety Research and Testing Center to form the Safety Research Center, with facilities at Pittsburgh and Bruceton, Pa. Subsequently, passage in December of the Federal Coal Mine Health and Safety Act of 1969 (Public Law 91-173) had a major influence on the activities of the new center. These activities were conducted under two main programs, Coal Mine Safety Research and Explosives Research. The Coal Mine Safety Research program was concerned primarily with two categories of hazards: health-related hazards associated with the mine environment, due to such factors as respirable dust, toxic gases and vapors, and excessive noise; and accidents due to mine fires, explosions, and roof falls.

Jan 1, 1972

THE object of this paper is to review certain features in connection with the mining of narrow lodes, say up to 20 ft. or so wide. The types of ore-body to which it is intended to refer are those which occur. chiefly as fissure or shear-Iodes-that is, those lodes which are to be found in belts of country which have been subjected to dynamic stresses, resulting in the formation of cracks and fissures, into some of which has been concentrated sufficient metal-bearing material to form ores. Very frequently one of the walls of such a lode is found to be a fault, or plane of differential movement.The first point which comes up for consideration is the shaft and its position. From the information afforded by the prospecting which has been done on a lode relative to the dip, nature of country, &c., the position of the main hauling shaft can be determined. For purposes of general utility the hangingwall is generally chosen, if a vertical shaft, though, on account of freedom from creeps, the foot-wall would be safer. Vertical shafts are preferable to underlie shafts in many ways; but wherethe lode maintains a flat dip the cost of cross-cutting at the various levels becomes very heavy'. This difficulty may to some extent be modified· by sinking a vertical shaft in the hanging-wall...

Jan 1, 1912

By J. H. Adkins

The goal of this program was to produce a set of baseline health and safety training materials that could be used by the metal/nonmetal mining industry to reduce injuries and to comply with federal training requirements. The materials developed are arranged in a two level outline format. The first level provides the title, course goals, background and topical outline while the second level provides a detailed outline of the course content. Visuals, designed to portray miners in a positive, attractive fashion, were done in simple line drawing so they would reproduce for handouts without loss of quality. Each of the required units in the Baseline Guides have one or more self-checks. These are designed to be suggestive of evaluation techniques the users can develop for themselves. An instructors guide and a mining terms glossary are included. In a second phase the program developed performance based training guides for Annual Retraining and Experienced New Hires in the Underground Salt Industry.

Jan 1, 1983

By Yvone Franco Crosato

The dense population of Hong Kong requires the construction of tall buildings in reclaimed areas or perched on the slopes of the many hills. The large loads to be supported are carried by deep foundations. Many of those are bored piles, to rock, of diameters up to the 3.0 m. of today.

Jan 1, 2000