Search Documents

By G. Sauer

"More Skill is needed to avoid rather than to handle heavy ground loads." This finding, from a tunneling engineer of the nineteenth century, is still relevant today with all advanced sequential excavation and support methods available whether they are applied in the vertical or horizontal direction. Balanced contractual agreements and documents are important since they provide the spirit and climate at the site. This article aims to describe the means and measures for 'hand mined' shaft and tunnel support as they are available today. Some special construction elements and methods with a perspective in recent developments in order to avoid getting stuck in conservatism are presented as well. If we don't allow new methods, means and measures we may end up with the famous quote "Only women who have already proven they are able to give birth to a healthy baby are allowed to become pregnant!"

Jan 1, 2003

By S. Yamashita

Recently in Japan, unexpected degradation (surface subsidence) at old underground quarry sites, such as 'Ohya-Ishi' (pumice tuff) pit field has often been occurred. At these quarry sites, the excavation was started 20 or 30 years ago with mechanical chain cutter and the Room and Pillar method, and stopped 7 or more years ago. Therefore, a reliable method has been required for an estimation of long term mechanical properties of the rock and for an observation of a stability of rock-pillars or structures. In this study, creep tests under uniaxial compressive load were carried out on the 'Ohya-Ishi', with the aim of estimating the long term stability of the rock. From these results, a creep mechanism of the rock was discussed using the failure mechanism hypothesis proposed by Bieniawski and by others. On this basis, critical time to failure was predicted by the relationship between the logarithm of life time and stress ratio of the sustained axial creep load. Additionally, outline of the monitoring system of AE/MS activity in the field, which have set by the Ohya Aria Consolidate Public Corporation and the others to predict or to prevent the degradation of those residual pillars, is to be reported. Key words : Ohya-ishi, Pumice tuff, Mine pillar, Long term stability, Creep, Critical time

Jan 1, 1996

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 Anthony Treasure

El presente trabajo señala la aplicación de la tecnología EMEW® para la recuperación de metales preciosos a partir de soluciones cianuradas diluidas que contienen plata y oro. La tecnología consiste en un proceso de electroobtención que ha sido desarrollado específicamente para la recuperación de metales en una sola etapa a partir de soluciones, hasta concentraciones de metal muy bajas, de forma que recupera plata y oro a partir de soluciones de lixiviación. Asimismo, este sistema ofrece beneficios como: menor costo de capital, costo de operación, simplificación de proceso, bajo riesgo técnico, mayor recuperación de plata, así como pureza del producto.

Sep 12, 2005

By Barry A. Hillman

The rapid evolution of computer and field sensor technology is now providing the ability to integrate mine and office operations. Digital maps and mine plans as well as CAD and GIS can be transferred to ruggedized field computers for development of real-time mine surveys and real-time GPS machine navigation and monitoring. Surveyors can insure that their surveys are accurate before returning to the office. Engineers and surveyors are also able to upload field computer-based surveys to mine planning software and directly to mine equipment including shovels, drills, and dozers providing the operator of the equipment with a real-time view of their work space. Production information can be transmitted through dispatch and/or centralized mine servers to update mine plans with mining progress and production data. Static mine models then become a dynamic element of operations, providing greater use of information that emphasizes the spatial aspects of the mine by providing real-time maps, productivity charts, and graphs. This information can be disseminated through various mine communication systems to provide operators and management with real-time feedback as well as daily and weekly reports. Integrated systems now being used in extensive trials are reporting productivity increases of 4 -7% or more thereby providing rapid payback to the mine.

Jan 1, 1998

By McLeod RL

The Tolukuma gold-silver prospect is located approximately 100km N of Port Moresby in the Central Province of Papua New Guinea (PNG). Epithermal "adularia-sericite" style mineralisation crops out over 1200m within an en echelon quartz veined zone 1 to lOm wide. At a 4g/t cut-off grade, a geological resource of approximately 1.47Mt @ 13.77g/t Au is indicated from 38 diamond drill holes completed since discovery by Newmont Pty Ltd in September 1986. At a regional scale, Tolukuma miner- alisation appears localised in a dilatant zone at the intersection of a 1150 magnetic structure, and the western margin of a N-S trending graben which is filled by a Pliocene volcanic complex contemporaneous with the Mt Davidson Volcanics 30km to the W. A l0km diameter circular Landsat feature, which may reflect magma emplacement at depth, occurs immediately N of Tolukuma and nearby mineralisation. Mineralisation at Tolukuma occurs in sub-vertical quartz veins at, or adjacent to the faulted contact between Pliocene basic and intermediate volcanics/intrusives, and quartz mica schists and phyllites of the Cretaceous Kagi Metamorphics. Most veins display evidence of multiple episodes of brecciation and textures indicative of cyclic boiling, including crustiform rhythmic banding and quartz pseudomorphs after platy calcite.

Jan 1, 1991

By T King

This paper reviews the changes in the coal industry over the past 30 years and attempts to predict the trends over the next ten years. The last 30 years have seen a steady concentration of production into fewer, larger mines, which operate on 3: more continuous basis, and a major increase in productivity per employee. Coal exports have increased from zero to almost half the country's total production. As well as major changes in exploration and mining equipment and the increasing use of computer tools, the industry now operates in a relatively new regulatory and commercial environment.   Safety legislation now requires the writing and enforcement of policies and procedures by the mining companies, rather than adherence to inflexible regulations enforced by an Inspector. Accident rates have decreased dramatically. The transition from coal mining licences to permits, requiring landowner consent and resource consents, is well under way. Environmental controls are now an essential aspect of the industry.   Equipment suppliers now offer maintenance services, production guarantees and flexible financing.  Contract miners offer mine design and restoration as part of the contract. In a similar approach, Solid Energy now offer an ash disposal service and assistance with resource consents to their customers as well as investment in technology to ensure a consistent product to demanding specifications. Solid Energy has proposals for energy centres which install and operate the coal burning appliances and simply sell energy to the customers. The next 10 years should see an intensification of these trends of bigger mines, more exports and greater technology and a 'package' approach to customer service.

Jan 1, 1997

By Reeves M

A review of the literature available in English on kriging and geostatistics is given with the references cross-classified by their subject matter for convenience and ease of use.

Jan 1, 1979

By Robin J. Batterham, Dave J. Robinson

The history of mineral processing in general and flotation in particular is long and has always been tied to mining methods of the day. Building on the ever-improving fundamental understanding of the underlying science, the most significant trend in flotation has been the putting into practice the learnings from trailblazers such as Professor Fuerstenau that has given the confidence that enabled an ever-increasing scale of operations. There is, however, doubt this ongoing trend is enough to maintain the economics against global trends such as that of falling grades, increasing mining costs, pressure on water supply and demand, rising energy demands needed for mineral processing, and a focus on whole of life value and mine legacy issues. In addition, we see that globally, the social license to operate for mining (and hence mineral processing) is far from secure and, at the very least, is under much more rigorous scrutiny. In this paper, we comment on the ramifications of broader uptake of more sustainable mining for mineral processing methods and address the specific question of whether recent progress in in-place recovery will lead to a timely breakthrough. The answer proposed is that this is possible in the next 10–20 years but in the meantime, the focus is just as likely to be on removal of waste (beneficiation) much earlier in circuits. Either way, mineral processing and flotation, as we know it, will change significantly.

By D. Malovichko

Seismic events and pillar failures observed in two platinum mines in the Rustenburg area, South Africa, were investigated. We studied the sources of approximately 300 largest seismic events recorded in 2009. Moment tensors of these events were estimated from amplitudes and polarities of P- and S-waves. The inverted mechanisms contain isotropic implosive components in many instances. Analyses of uncertainty of the moment tensor solutions confirmed the significance of the implosive component in general. Several documented cases of pillar failure were considered in detail. For each of these a seismic moment tensor was calculated from an elastic stress model assuming an instant removal of a failed pillar. The geometries and magnitudes of the theoretical seismic moment tensors are in agreement with the observed (i.e. inverted from seismic data). The results indicate that either pillar failure or fracturing in the proximity of the reef (within a fraction of the dominant wavelength of seismic waves) are responsible for a significant portion of the large events recorded in these mines.

Jan 1, 2012

By M. J. Little

Potgietersrust Platinums Ltd (PPRust) is Anglo Platinum?s only open pit operation. The major slope stability concern at PPRust is rapid, small-scale brittle failure on the west wall of Sandsloot open pit. In order to improve safety and mine more economically, a comprehensive slope monitoring strategy has been implemented. In the last 3 years four new state-of-the-art monitoring systems have been installed namely an ISSI microseismic monitoring system, a GeoMoS automated prism monitoring system, prismless Riegl laser scanners and a GroundProbe slope stability radar (SSR). Groundwater monitoring and visual monitoring have also been improved over the same time period. To complement the visual inspections, SiroVision digital photogrammetry is now used for predicting where future failures may occur. All these monitoring tools provide primary monitoring which is used to identify high risk areas. The SSR is then set up in that area to provide early warning of failure so evacuation can be successfully done. Fault tree analysis has proved that with this comprehensive slope monitoring strategy the geotechnical risk at PPRust is greatly reduced, allowing mining to continue safely and economically in challenging conditions.

Jan 1, 2006

Les Mines Inmet ? La Division Troilus exploite une mine d?or à ciel ouvert depuis 1996 et produit un concentré de cuivre. La Division Troilus est localisée à 175 KM au nord de la ville de Chibougamau? au 51 parallèle.

Feb 1, 2008

By Frank Rieber

THE study of earthquakes long ago developed the fact that by studying the travel times of the various groups of waves from the same earthquake, as received on seismographs at varying distances, major discontinuities in the earth's crust could be reasonably well defined. Using this original discovery, and adapting the mathematical methods originally devised in seismology for determining the depth below the surface at which such discontinuities occur, other investigators were able to develop a new branch of seismology which promises to be extremely useful in extending the boundaries of our information on local conditions below the earth's surface. As an outstanding example of the applications of this work, we have the so-called "seismograph" exploration of the Gulf Coastal region, which has resulted in the discovery of a large number of salt domes, from many of which oil fields may be developed. The original seismological investigations, from which different major discontinuities in the earth's crust were deduced, as well as these later successful experiments in locating salt-dome structures, involve relatively simple problems. In each case we are dealing with surface materials in which elastic waves will be propagated with a fairly definite velocity. Under this material we have something quite different, in which the elastic waves will be propagated with a much higher velocity. The transition from one medium to the other is likewise relatively abrupt. For example, in the Gulf Coastal region the sedimentary formations have a velocity of 6000 or 7000 ft. per sec., while the velocity of elastic waves in the cap rock of a salt dome may exceed 15,000 ft. per sec. Under such conditions, delineation of the formation is a relatively simple matter, and, furthermore, there is very little opportunity for ambiguous results.

Jan 1, 1928

By Johannes Moeljono, Werner Wenzel, Heinrich Wilhelm Gudenhau

As an important mechanism for increasing production of the suction-draft-sinter process, it has been shown that gas permeability through the sinter layer plays an important role. Methods to increase production rates have been indicated and suggestions for carrying out the process have been made to improve the rate of production, reduce the fuel consumption, and at the same time obtain a uniform sinter. Laboratory experiments were conducted at the Institute for Ferrous Metallurgy of the Technical University at Aachen to illustrate these methods. Methods of Increasing Gas Penetration Through Sinter Layers The following are of fundamental importance in determining the process cycle during the sintering of iron ores: 1) Generation of maximum temperature, since its form and range determine sinter quality. 2) Propagation velocity of the temperature maximum which controls the attainable output. 3) The convective heat transfer which influences the velocity of travel of the temperature maximum.

Jan 1, 1974

By I F. Bell, K P. Hammerschmid

Well planned and executed environmental management plans can reduce life-of-mine operating costs and the need to deal with major environmental issues at the time of mine closure. With proper planning during the exploration, feasibility and execution phases of a project, final closure costs can be reduced. The reduction of closure costs should be considered during exploration and initial feasibility studies and when process facilities, waste rock dumps and tailings impoundments are designed. During the mining of the resource, closure cost reduction will depend on effective and efficient environmental management plans for ongoing land clearance, segregation of mine waste materials, management of mine site water and workshop wastewaters, and the establishment of progressive rehabilitation strategies. These issues are the responsibility of planning, production, technical support and maintenance personnel at an operating site. The successful implementation of environmental plans will ensure that all impacts are reduced and that closure issues with major cost implications are addressed prior to closure of the mine.

Jan 1, 1995

The use of black and white and colour infrared film in remote sensing of natural resources is reviewed. In heavlly-forested areas such as New Zealand, the main value of the method is in surveying the vegetation cover to detect the existence of plant communities characteristic of specific geological formations. By contrast in arid areas of Australia where the vegetation cover is sparse and where rocks and soils are well exposed, the method can be used in detecting different rock types or other geological differences.

Jan 1, 1972

[ ]

Jan 1, 2009

By J R. Lang, J K. Mortensen

The Canadian Cordillera contains numerous classic porphyry deposits and several unusual subtypes, including the alkaline suite of porphyry Cu-Au deposits and the Tombstone magmatic suite and associated Au¦W deposits. The alkaline suite formed in collisional settings in island arcs whereas the Tombstone suite was emplaced in an active fold and thrust belt in a continental arc. In addition to different regional settings, these suites differ in the type of underlying basement, metallogeny, and the styles of mineralization. Both magmatic suites were emplaced over short intervals, probably in response to specific tectonic events. In the case of the alkaline suite, the tectonic event promoted magmatic processes suitable for the formation of porphyry Cu-Au deposits. The tectonic environment is less well constrained for the Tombstone suite, but the result was the formation of distinctive porphyry and intrusion-related Au¦W deposits.

Jan 1, 1995

By R. Schulz, K. King

Concentrating Line 6 just went down again. The control room operator checks the graphic display. Only one piece of equipment shows an alarm. Clicking on the ball mill icon, he discovers the culprit was the low flow lube switch. The flow looks okay now, but it is the third time this week the switch has stopped the line. Maintenance is called, the switch replaced and the line is up running again. Sending the right person to the right spot immediately can save hundreds of hours of downtime every year. This paper discusses the principles behind implementing smart First-Out Fault Detection to dramatically reduce equipment downtime in new, or existing control system architectures. Methodologies are presented to maximize the system benefits, while minimizing development costs. Case histories are presented for a number of successful implementations in mineral processing plants.

Jan 1, 2001

By Heribert F. Broicher

By the very nature of mineral deposits the quality of the raw material generally fluctuates and should be known for optimum processing. Early classification, for example, of limestone into road-metal grade or lime grade or of run-of-mine ores into high grade, low grade and waste as well as information for blending or for dosage of reagents are prerequisite for economic processing. Non-contact, real-time and on-line rock identification or assessment of quality parameters can be realised by introducing the analysis of laser-induced fluorescence (LIF) into the mining industry. LIF analysis is an optical method evaluating the basically known photoluminescence properties of matter, however, extending the application into hitherto unimagined fields by use of high-energy pulsed lasers and time-resolved analysis of fluorescence in the ultra-violet, the visible and near-infrared domains of light. LIF analysers and test work in a limestone quarry and a cement plant in Germany as well as in an iron ore mine in Sweden are described. First results of test work are available and proof this technology to be promissing.

May 1, 2002