Search Documents

By Tuncel M. Yegulalp

The objective of this study was to categorize mining operations in the stone, and sand and gravel industries into areas of similar ground control functions and define initial factors affecting operational safety in each area, by means of utilizing publicly available data, telephone interviews and on site observations. The findings and recommendations presented in this report are based on the information collected during the two phases of the project. They also contain, in part, the collective qualitative opinion of the operators with respect to government rules and regulations on ground control safety and the implementation of these rules and regulations by government inspectors.

Jan 1, 1981

By L. Clark

Despite near-record commodity prices, the mining industry continues to search for ways to maintain profits in these times of steadily increasing energy prices and steadily decreasing grades. The pressure is still on today’s miners to continuously improve their operations because they know that one day prices too will drop. Some, however, have seized the opportunity to employ systematic methods to reduce costs and increase the efficiency of their workforce and equipment. As a result, closer attention is being paid to scheduling and the value that could be added by defining the extraction sequence that maximizes the net present value [NPV] of a project. This paper will discuss the challenges faced by Newmont Mining Corporation [Newmont] at its operations and the application of sophisticated software tools and methods in its search of solutions to this problem.

Jan 1, 2007

By J. Matos e Silva

"Abstract The paper refers five examples of executed diaphragm walls with one to five levels of anchorages. For each example a comparison is made between the results of the design using the traditional criteria and the ones obtained by using the Eurocode 7 and the Portuguese Norm related to the EC7 (NP EN 1997-1 2010), as the Eurocodes consider the possibility of each European country to adopt their own geotechnical parameters as these may vary from one country to another. A comparison is also made with the behaviour of these diaphragm walls during its construction phase; so the values from the design that were adopted in the construction are listed in tables 2 to 6 in the “Construction Options” columns. From the referred examples the author presents his conclusions.1 - INTRODUCTIONIn the so-called “traditional criteria” the soil parameters (dry unit weight, angle of internal friction and cohesion) have values obtained through tests or empirically. It is assumed that the characteristic values of the soil parameters adopted in Eurocode 7 are equal to the soil parameters adopted in the calculations by the “traditional criteria”. In the present paper the design according to the EC7 was made considering only the ultimate limit states and the respective Cases A1 and A2.The partial coefficients used for the actions in the present paper were those on Table 1:2 - CONSIDERED EXAMPLESThe five examples correspond to the situations of figures 1 to 5, and the respective results are summarized in tables 2 to 6.For all the considered examples, that are case histories, a simplified method published by Matos e Silva (March 2000) was adopted. This method attains good performances when compared with other more sophisticated ones as the finite elements and the elasto-plastic methods as described in a paper published by Matos e Silva (2000). All the obtained values were compared between them and with the so-called “Construction Options” that were the values adopted by the designers of the considered examples. For the wall bottom length calculation two possible situations were envisaged:"

Jan 1, 2014

By P. P. Rosario, D. M. Maijer

The primary crusher is a key component in the comminution process applied in open pit mines. A collaborative research project between the University of British Columbia and Highland Valley Copper (HVC) was conducted aiming at understanding gyratory crusher liner wear in the overall context of the crushing process. This paper presents an analysis methodology applied to data collected using a laser-based tool for assessing wear in gyratory crushers. Data from the wear measurements was correlated with crusher production information such as current draw and throughput. As a result of the knowledge developed during this work, an innovative way to evaluate crusher liner profiles was created and new mantle profiles were designed. This led to a reformulation of HVC’s standard liner management policy with a resulting estimated annual savings of 13% in total crusher liner cost and a 15% reduction in liner replacement downtime.

Jan 1, 2006

By Robert L. Lappi

Eight interburden handling concepts are developed for multiple seam area mine stripping operations in central and western United States. They are based on data gathered and analyzed during field surveys, literature reviews and visits to state requlatory agencies in five states. It is concluded that improvement of reclamation practices through selective interburden handling techniques is possible at lower operating costs than currently incurred. Specific multiple seam mining systems are discussed in this report.

Jan 1, 1980

Severe whipping of shuttle car trailing cables occurs when the car stops suddenly or reverses direction. This causes cable damage, and can seriously injure personnel near the cable. FMC has contracted with the U.S. Bureau of Mines to design, build and demonstrate a reel control system that will significantly reduce or eliminate whipping. II. CONCLUSIONS Results of engineering effort show that the following conditions are primarily responsible for the whipping problem. Causes may exist individually, or in combination.

Jan 1, 1972

By R. Bauer

Adaptations and redesign of the existing already very successful and proven road milling machine concept and technical innovations such as an optimized, specifically for mining application developed cutting drum, cutting housing design and cutting tools, high manoeuvrability achieved via a tight turning radius, a three disk clutch system and a cutting drum drive that allows for the acceptance of higher loads, a complete reinforcement of the chassis to withstand higher vibrations and torque, the installation of increased engine power via a modern drive unit, a specifically for mining/construction applications developed operator’s platform and finally a redesigned air intake system and the adaptation of the levelling system resulted in far more cost effective and advantageous capabilities of Wirtgen Surface Miner in soft to medium hard mining and construction applications. As the achieved results show for the first time in modern surface mining history mechanized cutting is capable to compete successfully against traditional drill, blast/ripping and other conventional mining methods.

Jan 1, 2007

By Irving Hartmann

Falls of roof in coal mines and means of preventing them have been subjects of study for many years, and an extensive literature has resulted. Usually each individual paper has placed emphasis on one phase of the subject, such as fatalities, nature and extent of nonfatal injuries, methods of tembering (particularly in rooms or other wide places), safety along retreating rib lines, and methods of causing falls in abandoned areas. It is only in recent years that there has been persistent question as to why

Jan 1, 1941

By W. C. Blanchard

Time Domain Reflectometry (TDR) is a remote sensing technique using active backscatter. This technique is applicable to the testing for faults and multiple partial faults on cable. The battery operated hardware developed on this con¬tract has tailored this technique for testing of mining equipment trailing electrical cables. The processing of-t-he back-scatter is accomplished using a microprocessor. The visual output from the hardware to the operator is; the type, magnitude and distance to the cable fault in a numerical format. This greatly simplifys the use of this techniques for the operator.

Jan 1, 1980

By Charlie Wyche

The British Solomon Islands Protectorate continued developmental work on bauxite deposits on the Islands of Rennell and Vaghena. A feasibility study was completed by Mitsui Mining & Smelting Co., Ltd., and Pacific Aluminum Ltd. (a subsidiary of Conzinc Riotinto of Australia Ltd,), and negotiations with the Government were in progress. The Government will receive a 25% share if the project is realized. It was estimated that the Islands contain 60 million tons of bauxite with an alumina content of 45% to 50%.

Jan 1, 1980

By Victor C. Bryan

One of the most sought after answers in any consideration of blasting activities relative to mines and quarries is how to safely and efficiently use explosives. While that discussion might be relatively straightfonvard in a “site specific” situation. it becomes more complex when viewed from a broad geographic perspective. Such is the case in considering the operations of one United States producer of crushed stone with surface and underground mines spread over a thirteen state area. Differing geologic environments set conditions that dictate to the blaster as now specifically to get optimum results from the blast hole. This treatise is a discussion of the various methods, materials, and principles used in conducting such blasting operations.

Jan 1, 1991

By G J. Massoth, K Faure, A G, R G. Ditchburn, I J. Graham

From modest beginnings in 1996, research into the mineral potential of New ZealandÆs Exclusive Economic Zone has progressed into a major multidisciplinary component of GNSÆs recently funded 6-year æMineral Wealth of NZ and its EEZÆ Programme. In excess of $7.5 M of research funding has been expended, plus $10 M leveraged via collaborations with NIWA (NZ), NOAA (USA), JAMSTEC (Japan), U. Kiel (Germany) and ANU (Australia), whose scientists have contributed hugely to research cruises, as well as subsequent analysis and publication. The 1999 NZAPLUME I cruise was the first research expedition to systematically locate, and chemically characterise, submarine hydrothermal venting associated with arc volcanoes of the southern part the Kermadec intra oceanic arc system. This was followed by the 2002 NZAPLUME II and 2004 NZAPLUME III cruises to the mid- and northern-sections of the Kermadec arc, respectively. Combined, these cruises have surveyed 1300 km of the volcanic chain (from Whakatane to Monowai), including 34 major volcanic centres. Together with concurrent surveys in the Tonga arc, this is now the longest continuous stretch of intra oceanic arc to be surveyed for hydrothermal emissions. Most of the volcanic centres are characterised by simple cones although 30 per cent contain caldera complexes, and compositions range from basalt through to rhyolite. Massive sulphide mineralisation has been recovered from several volcanic centres in the southern Kermadecs (Clark, Rumble II West and Brothers), suggesting the existence of significant Au and base metal bearing deposits along the arc front.

Jan 1, 2005

By Peter Claus

In the last years, supported gold catalysts with particle sizes smaller than 10 nm have attracted a lot of attention. While gold bulk metal is rather inert in chemical reactions and, thus, is of low interest for catalysis, highly dispersed gold particles supported on oxides as TiO2 or ZrO2 show surprisingly high activities in some reactions important for the chemical industry. The oxidation of carbon monoxide at low temperatures is mainly used as model reaction to study the unusual properties of gold catalysts [1]. On the other hand, to evaluate the catalytic potential of gold, other chemical reactions which allow to control also the selectivity have to be considered. The selective hydrogenation of ???-unsaturated aldehydes to allylic alcohols is of both commercial relevance (e.g. in fine chemical and pharmaceutical intermediate production) and specific scientific interest [2]. Note that thermodynamics favors hydrogenation of the C=C over the C=O group (stronger negative free reaction enthalpy of 35 kJ/mol), and for kinetic reasons the C=C bond is more reactive than the C=O group. Thus, in the presence of most of the conventional hydrogenation catalysts, based on Pt, Rh or Pd, -unsaturated aldehydes such as acrolein and crotonaldehyde are hydrogenated predominantly to the saturated aldehydes and only to a minor extent to unsaturated alcohols. Therefore, it is desirable to find catalysts which are able to control the intramolecular selectivity by hydrogenation preferentially the C=O group while keeping the olefinic double bond intact (Fig. 1).

Oct 1, 2003

By Irving Hartmann

Falls of roof in coal mines and means of preventing them have been subjects of study for many years, and ran extensive literature has resulted, Usually each individual paper has placed 'emphasis on one phase of the subject, such as fatalities, nature and extent of nonfatal injuries, methods of tembering (particularly in rooms or other wide places), safety along retreating rib lines, and methods of causing falls in abandoned areas. It is only in recent years that there has been persistent question as to why

Jan 1, 1941

Impala Platinum?s No.16 Shaft mine is currently under construction and is expected to reach full production of 256 500 tons per month by 2014. Mining will start at 1 260 m below surface with a maximum mining depth of 1 535 m where virgin rock temperatures of 56.6°C will be experienced. As a result of depth, high virgin rock temperature and narrow reef mining, an expected total of 31.5 MW[R] of air cooling capacity will be required to achieve acceptable underground conditions. This will be achieved by cooling mine intake air in a single dedicated air cooling installation located on surface. The compact installation includes air cooling spray chamber, refrigeration machines, condenser cooling towers, evaporator and condenser water reticulation as well as all electrical and control systems. Construction and commissioning of the first phase of this air cooling installation has recently been completed on a turn-key contract basis.

Jan 1, 2009

By B. R. Reddy, Y. V. Swamy, B. V. R. Murthy, H. S. Ray

The Ni oxide was reduced with a CO-CO2-N2 gas mixture and the effects were observed of process variables such as roasting temperature, time and CO partial pressure. Extraction of over 90% of Ni was achieved by ammoniacal leaching of ore that had been reduced for 1 h at 760 degrees C under a gas mixture with a volumetric CO/(CO+CO2) ratio of 0.57. The kinetic data were found to conform to the Ginstling-Brounstein equation. The applicability of this model was confirmed by evaluating the apparent activation energy with the use of independently constructed differential and integral plots, which showed an excellent match

Dec 1, 1995

By A. B. Cecala

Over the past decade, a substantial effort has been made to improve the air quality inside enclosed cabs of both underground and surface mobile mining equipment to reduce respirable dust exposures to the equipment operators. As part of this effort, the National Institute for Occupational Safety and Health, (NIOSH) completed a comprehensive laboratory study which determined the significant factors for cab filtration and pressurization systems. From this information, a major underground mining equipment manufacturer designed a filtration and pressurization system which was incorporated into the enclosed cabs of its equipment. A long-term evaluation was performed on the effectiveness of this filtration and pressurization system to improve the air quality in the enclosed cabs of two different pieces of equipment, being a face drill and a roof-bolter machine, at an underground limestone mine. This long-term evaluation demonstrated a significant reduction in dust levels comparing outside to inside cab respirable dust concentrations. During this evaluation, a modification to remove one of the filters on the roof-bolter machine simplified the design without sacrificing the system?s efficiency. Testing using particle count instruments performed during non-production time periods on both pieces of equipment indicated Protection Factors greater than 100 when comparing respirable-sized dust particles inside the enclosed cab relative to outside.

Jan 1, 2012

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

By Tim Q. Haldane

The ability to efficiently process lowgrade ores has allowed the Gold Fields Mesquite Mine in Imperial County, CA to expand from a 2.1 Mt/a (2.3 million stpy) rate in 1986 to its present 7.3 Mt/ a (8 million stpy) processing rate. Increased tonnage demands led to the 1989 construction and startup of a dump leach pad to supplement the existing heap leach operation. This resulted in an excellent opportunity to compare the two processes at the same operation. Additional operating costs associated with the crushed ore heaps are justified through enhanced recoveries, even at very low ore grades. Gold Fields' Mesquite Mine is a gold heap leach facility located about 55 km (35 miles) east of Brawley in southeastern California. Five open-pit mines will be developed over the projected life of the property, covering a total area extending to a maximum of 5.5 km (3.4 miles) to the east and west, and 2.4 kin (1.5 miles) to the north and south. Mesquite will process 7.3 Mt (8 million st) of ore and produce more than 6.2 t (200 000 oz) of gold in 1990.

Jan 1, 1990

By A J. Broome

Since 2003, there has been an unprecedented growth in the demand for engineering, technical and project services in the mineral industries. This demand for services became evident in Australia earlier than many other markets and has since spread globally. This growth has created significant issues for the strategic direction and planning by the service provider. Such strategic questions include:- how fast to grow, how to recruit, train and integrate new staff, what market sectors to service, the selection of targeted customer sectors and managing strategic growth with short term demands and commercial reality. These factors are discussed using in depth experiences and examples that illustrate these strategic approaches. The relevance of this new industry environment to New Zealand services will be highly discussed.

Jan 1, 2007