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By Linli Wu

During the measurement of contact angle, a misty band was observed near the substrate. Hsien-Nan Ho and Shinn-Tyan Wu thought this was because the oxygen atoms on the interface migrate to the droplet surface to form an oxide band near the substrate. But from our experiments misty band appeared before the drop reach to the substrate. Theoretically speaking, the oxygen partial was the same everywhere in the vacuum furnace. So there was no condition to provide enough oxygen forming oxide. This appearance would be explained more reasonably with the optics principle. Most reflected light would be absorbed by the substrate and the light cannot reach the observation area, so the misty band formed.

Jan 1, 2006

By Victor V. Nazimko

Long term stability of the pillars that have been remained after R&P extraction causes postponed subsidence. To prevent unforeseen subsidence and to diminish postponed subsidence 25-50% new method for its control has been developed by the author. It supposes to use drilling and blasting technology and other original approaches. New method has been fulfilled through the holes being drilled from the surface or from the active underground openings. Explosives had been charged into the holes and were blasted. This had increased bulking factor dramatically and prevented natural caving of the strata. Physical scale modeling corroborated efficiency of the new approach. The bulking factor has grown from 0.0623 to 0.1185 and surface subsidence has been diminished from 1.1 m to 0.2 m or 5.5 times.

Jan 1, 1996

By Luis Valentim, John E. Wiegand

Highwall or face profiling has long been used to facilitate the design and placement of front row blastholes to ensure optimum burdens. Traditionally, a large number of laser measurement points obtained from the rock face or highwall, were input in profiling software packages. This method can be time consuming and requires access to the rock face with a complete view of the highwall, to be successful. Stereo photography has also been used to generate the rock face surface, but this method also requires access to the highwall (and pit floor in some instances) for measurement of reference targets or points.

Jan 1, 2016

This Department handles all ores prior to blast-furnacing, the object of the operations being to mix the lead-bearing material with fiuxes, eliminate sulphur from the mixture, and produce a homogeneous sintered product which is chemically and physically suitable for treatment in the blast furnaces.During the financial year ended the 30th June, 1937, the tonnage of charge treated was 458,960 tons, containing some 183,470 tons of lead and 8,504,000 oz. of silver.The quantities of the principal components of the charge treated were as follow:-

Jan 1, 1937

By O. Nyandoro, K. Khoza-Shangase, M. Madahana, N. Moroe

"Occupational noise-induced hearing loss (ONIHL) is classified as the leading work-related disability in the mining industry. ONIHL has a negative impact, on not only the health and occupational productivity of affected individuals, but arguably also on the country’s mining industry and economy. Hearing conservation programmes (HCPs) are an effective strategy in the management of ONIHL. However, current literature indicates that HCPs are not achieving the anticipated and desired outcomes in the South African mining sector despite the efforts focused on the management of ONIHL. Therefore, the purpose of this study is to propose the use of a feedback-based noise monitoring model as a tool for monitoring and managing ONIHL in the South Africa’s mining sector. This model is a basic static feedback model with practical applications such as estimating, monitoring. and providing quantitative information to aid miners, mining administrators, and policy-makers in decision-making around HCPs. Additionally, the model could form part of an early intervention and management strategy for ONIHL in the workplace. The strength of this model, although currently static, is that it encompasses all the pillars of HCPs and takes into account the policies concerned with the management of ONIHL in the mining sector. IntroductionHazardous noise levels (above 85 dBA) in the workplace place exposed employees at risk of developing a disabling occupational noise-induced hearing loss (ONIHL). ONIHL is the ‘partial or complete hearing loss in one or both ears as a result of one’s employment’ (Nandi and Dhatrak, 2008, p. 1). This type of hearing loss develops gradually as a result of being exposed to continuous or intermittent high levels of noise over a long period of time (McBride, 2004; Patel et al., 2010; Rappaport and Provencal, 2001). A hearing threshold below 40 dBs is classified as a disabling hearing loss (Yadav et al., 2015), resulting in a hidden condition that does not readily manifest itself (Tye-Murray, 2009, p. 3). Dugan (2003) describes disabling hearing loss as the ‘most prevalent, least recognized and least understood physical disability’, while Copley and Frederichs (2010) and Hermanus (2007) argue that permanent disabling hearing loss is a major contributor to the global burden of disease on individuals, families, communities, and countries."

Jul 1, 2019

Amid some of the worst economic conditions that the mining industry has been faced with in more than a decade, the mood among the large crowd at the 114th Annual Northwest Mining Association?s annual meeting was surprisingly upbeat. More than 2,200 attendees showed up at John Asuaga?s Golden Nugget Casino in Reno, NV for the conference held Dec. 1-5. And more than 200 companies exhibited in 240 spaces, including SME and the Minerals Information Institute. The number of attendees and exhibitors were the most for the conference in more than 10 years. The conference was held in Reno/Sparks for just the second time in its illustrious history but began under the cloud of global financial turmoil. Prior to, and during the conference, the industry news headlines were grim, to say the least. An alarming number of mine plans and expansions had been put on hold; hundreds of miners across the United States had been or were in the process of being laid off; commodity prices were falling and some of the biggest mergers in the industry fell through while miners around the world put the brakes on to take a wait-and-see approach. It was a painful time for many, but the downsizing actions taken by many mining companies was exactly what needed to happen, according to Industry Outlook Luncheon featured speaker Frederick Sturm. He is the executive vice president and chief investment strategist and member of Mackenzie?s Investment team. He has earned a reputation as one of Canada?s leading investors in natural-based companies and he also manages the Ivy Global Natural Resource Fund in the United States Sturm said that the mining industry has fallen hard and that he expects it to bounce back quickly, before falling hard again. In these tough times, he said, the companies that have pulled back on production early are doing the right thing in the long run.

Jan 1, 2009

By Bhaskar B. Thapa, Christopher Laughton, Michael P. Bruen

At Fermilab, located in Batavia, Illinois, a 4,000-foot underground complex of tunnels and caverns is being excavated on a decline of six percent, at depths of up to350 ft, below grade. The site geology consists of dolomitic and shale formations overlain by glacial till. Since the start of construction in March 2000, work to date has concentrated on the excavation and support of the Target Hall cavern, which is characterized by a low rock cover and a final lining of shotcrete. Ground vibrations, noise levels, and rock movement were monitored during excavation by drill and blast methods to prevent damage to experimental facilities, impacts on surrounding communities, and to allow evaluation of cavern performance. The cavern design was based on a UDEC numerical analysis that was validated during construction by comparison to encountered conditions and measured cavern movements.

Jan 1, 2001

By Robert L. Lappi

Volume I of this report described the demonstration of cross-ridge mountaintop coal mining. This document, Volume II, is intended for use as a supporting document to Volume I. This report describes the MATHMINE Mine Simulation System, a modularized software system used to support the demonstration of cross-ridge Mountaintop coal mining. The MATHMINE Mine Simulation System was used to generate mine plans for coal extraction at lowest cost. The functional details, data requirements and output of the software system are detailed here. The computer program was written in FORTRAN. One module which generates resource location data required the use of SAS?.

Jan 1, 1984

By A. Amiel

Tarkwa Gold Mine is owned by Gold Fields Ghana, IAMGOLD and the Government of the Republic of Ghana in a 71%, 19% and 10% ratio. The mine is operated by Gold Fields Ghana. This large, low-grade, open pit, gold mining operation is located in Tarkwa, in the Western Region of Ghana, approximately 320 kilometres by road, west of Accra, the capital of Ghana, West Africa. In the Financial year ended June 2007, the operation mined a total of 108 million tons of which 22 million tons was ore. The mined ore is processed through three gyratory crushers supplying two heap leach pads (north and south) and a carbon-in-leach (CIL) plant. Before the 6 Sigma project commenced, the current fragmentation was resulting in sub-optimal feed size to these crushers. It was decided to use 6 Sigma methodology to improve the fragmentation. A defect was defined as a fragmentation analysis indicating less than 95% passing 750 mm. The objective was to improve fragmentation in order to achieve a constant throughput to the north heap leach crusher of 1500 t/h, a 5% increase in pit loading efficiency and a 50% decrease in rock breaker hours, equipment damage costs and in-pit sheeting costs respectively. However, this was not to be achieved at the expense of grade control as Tarkwa is exploiting a low grade, high volume deposit and therefore ore dilution must be kept to a minimum. This paper is intended to take the reader through the various 6 Sigma phases of the project (define?measure?analyse ?improve?control), which have resulted in a 10% reduction in loading times, of which half has been attributed to improved fragmentation, as well as a substantial increase in blasted stocks. The focus has been on both drilling and blasting parameters as both processes had to be taken into account. These parameters are technical but personnel factors were also identified and dealt with as they arose. In order to measure the impact of any change in the process parameters on the fragmentation size distribution, cameras have been acquired. One has been installed looking into the bowl of the north crusher and the other one was dedicated to field observation, of individual blasts. Both are used for ongoing fragmentation analysis. At Tarkwa, mining efficiency is strongly dependent on good fragmentation as well as the presence of unblasted ?toes? on the pit floors. Crusher throughput depends on an acceptable ore fragment size. Compliance with plan for actual hole depths was temporarily monitored by manual hole dipping, but this is now being replaced with a fully automated drill data management system developed by Sandvik and Modular Mining. The Six Sigma methodologies, using control charts based on data collected in the field, allowed the mine to improve methods for the control of blasted material. It also enforced the implementation of a quality control programme encompassing the entire drill and blast process.

Jan 1, 2008

By Jimmy Rodríguez Las Heras

Durante la explotación de los niveles inferiores en la mina Yauliyacu, se generaron dudas sobre la ubicación de las concentraciones de esfuerzos y sus relaciones con los estallidos de roca. En este sentido, se instala un sistema microsísmico donde mediante el análisis de la microsismicidad se elaboró los estándares que permitieron reducir los incidentes por estallidos de roca presente, así como la frecuencia, magnitud y daños a las personas, y equipo e infraestructura de mina, debido a la energía liberada por los eventos microsísmicos. Por ello, el presente trabajo señala los beneficios del uso del sistema de análisis de microsismicidad como la actualización contínua de la zonificación minera de acuerdo a la concentración de esfuerzos, procediendo al reforzamiento del sostenimiento como medida de prevención.

Sep 21, 2013

By G. L. Smith

The fundamental challenge facing mineral and metal companies is how to create sustainable value while operating within mandated strategic bounds, identified constraints, and variable market and economic conditions. This can be achieved by allowing the fixed physical nature of the mineral asset to drive definition of the optimal technical solution to mining and processing activities, and developing and resourcing a strategically aligned portfolio of production entities that creates flexibility to near- and longer-term business environment shifts, i.e. a production mix that allows variation of output to respond to short term market variation, within a long term context. The practical achievement of this outcome is enabled by the concept of strategic long term planning. The core elements of strategic long term planning in the metals and minerals industry, and the relationship between them, are expanded. The strategic long term planning framework is a logic construct that enables delivery of an optimized, strategically-aligned business plan from the mineral asset portfolio using a set of tools and techniques with a common language, standards, systems and processes to align decisions and actions on a cyclical basis.

Jan 1, 2012

By Davies S. G, Mackey L. C

The oxidation of iron and nickel sulphide concentrates, and the dominant sulphide minerals which comprise them, has been studied under ignition conditions using thermogravimetry (fG). The concentrates were derived from various minesites and they showed differing tendencies to ignite. Ignition temperatures ranged from 416 to 488°C and the extents of reaction, measured at 500°C, varied from 64 to 88 percent. The reactivity of the least reactivematerial was improved significantly by grinding. Particles <63/lm showed 85 percent oxidation compared with 55 - 65 percent for particles >63/lm.Examination of the individual sulphide minerals revealed that these materials also have significantly different degrees ofreactivity and are subject to particle size effects. For particles <45/lm, the ignition temperatures were as follows:ò pyrite and violarite 380 - 385°C; pentlandite 425 - 430°C; and pyrrhotite 470 - 475°;ò for particles >90 /lm, the ignition values were: pyrite 395 - 400°C;ò violarite 430 - 435°C; pyrrhotite 540 - 545°C; and pentlandite 560 - 565°C.Using the data on the individual minerals it was possible to rationalise the differing degrees of reactivity of the concentrates. The role of the most reactive constituent in initiating the ignition reaction has also been discussed.Finally, the results of this work were found to compare. favourably with the behaviour ofthe concentrates in industrial and pilot-scale flash smelters.

Jan 1, 1989

By B. Weyerman

U. S. Steel's Oak Grove Mine experienced several top hinge failures on their caving shields. It was determined that all the caving shields needed to be replaced with new caving shields before more thilures occurred. The cost and amount of time needed for several scenarios of caving shield change outs were compared. This paper discusses how Oak Grove Mine decided to and did change 126 caving shields in six specially designed jig stations underground during a longwall move using their own UMWA employees.

Jan 1, 2001

By Peter Chou

A total of 117 slope stabilization drilled piers were installed as part of a major hillside revitalization project. The 110-million dollar development, known as Stratford at Kenwood, included an 18-story upscale senior residential tower, a 3-story healthcare building, and 4-story condominium buildings, offering approximately 580,000 square feet of living space with panoramic views of Downtown Cincinnati, Ohio. In an effort to establish a flatter hillside plateau for the new 4-story condominium and to create a cut and fill balanced jobsite environment, an 800-foot long row of drilled piers and a 600-foot long multi-tiered shear key system was used to terrace existing 1.5H to 3H: 1V steep slopes and support the new fill. These slope stabilization features reduced the amount of spoils needed to be wasted off-site and mitigated the risk of slope instability. An ODOT/FHWA research indicated that spacing of stabilization piers and necessity of top-connecting elements are highly dependent on pier diameter, spacing, soil type, depth to potential failure surface, surcharge loads, and pier deflection. Due to pre-existing deep buried swales, various load combinations, and the complex mechanism of soil arching effects between adjacent piers, both analytical and numerical computer modeling was performed to estimate the loading on each pier. New generation multiplexed, 3-Dimensional, Micro-Electro-Mechanical-System based inclinometers were installed between selected piers to confirm the pier design, and monitor the fill placement, as well as long-term slope stability.

Jan 1, 2009

The Pilbara Block is a nucleus of Archaean rocks which lies in the North West Land Division of Western Australia, and it constitutes a mineral province that has been divided into two areas-the West Pilbara Goldfield and the Pilbara Goldfield.In the West Pilbara Goldfield two contemporaneous environments are represented by laterally equivalent volcanic and sedimentary successions which together comprise the Roebourne Group. The two successions are lithologically similar to the classical Warrawoona (volcanic) and Mosquito Creek (sedimentary) successions of the Pilbara Goldfield; but in the West Pilbara Goldfield there is no sign of the erosional break which separates the Warrawoona Succession from the Mosquito Creek succession. The Roebourne Group and the igneous rocks which have intruded it belong to the Archaean Pilbara System.Evidence of preconsolidation movement and igneous intrusion into unconsolidated sediment suggests that tectonism and igneous activity, localized along lines of fracture in an unidentified basement, beganbefore lithification was complete. Movement was primarily vertical, and persisted into the Lower Proterozoic.Vulcanicity and chemical sedimentation, accompanied by a diminution of detr:tal sedimentation, is thought to have caused a relative enrichment in the metal content of the middle part of the Roebourne Group; and the metal may have been remobilized during diagenesis and metamorphism, and localized in zones of dislocation formed both before and after consolidation of the sediments.INTRODUCTIONThe name "Pilbara" has been widely applied in the area under discussion, and to avoid confusion the various uses are summarized below.1. The town of Pilbara, now abandoned, was a centre of mining between 1888 and about 1914. It lies some 90 miles FJSK of Roebourne (Fig. 1).2. The original Pilbara Goldfield was modified several...

Jan 1, 1965

By David O. DeGagné

While mine backfill plants are becoming increasingly more automated and instrumented, especially with paste fill operations, underground backfill distribution systems have hardly changed over the years. While fill properties are appropriately measured in the preparation plants, as backfill enters the mine borehole, the technology for control, data gathering and reporting is somewhat lacking. Mines typically experience problems with borehole and pipeline plugging, pipeline bursting, bulkhead failure and exposed fill sloughing. With adequate instrumentation of the backfill system it is possible to obtain a complete, continuous and detailed picture of the entire filling operation from preparation to post-pour. Good data will, over time, provide the basis for needed improvements of backfill systems and will be essential to safer, more efficient and less costly fill practices. This paper will review the areas of the filling operations where monitoring would prove critical to eliminate failures such as pipelines, bulkheads, fill exposures, stope walls, etc. The types of monitoring systems currently available will be reviewed and potential areas for development will be highlighted.

May 1, 2001

By Garland Likins

Where soil conditions are favorable, augercast piles have significant economic advantages, but they also have some uncertainty due to the in construction methods. To confirm structural integrity, static testing can be performed on a small sample of piles. Other Non-Destructive Evaluation methods like Pulse Echo are frequently specified for a large percentage of the remaining production piles. However, such NDE methods require testing the pile after the grout/concrete has hardened. If problems are found, then the repair or replacement can be relatively expensive. The confidence in the quality of these piles can be improved by automatically monitoring the grout pumped as a function of depth during the grouting phase of installation. If a low grout volume is detected, the pile can be redrilled and regrouted immediately while the piling rig is still in place and the grout still fluid. This considerably reduces remedial costs. To be effective, such installation monitors must accurately determine both grout volume and depth during installation and be rugged simple to operate. Such an equipment can be of great help to the installation crews. The assurance gained may reduce the need for subsequent NDE tests. The quality of inspection of driven piles depends heavily on the inspection personnel. While inspection is critical in a good installation, it is sometimes assigned a low priority. Inspection personnel in many cases are technicians with little pile experience. They may not understand the project needs or even how the pile driving equipment works. The task is often monotonous and any distraction makes accurate record keeping difficult. In some cases inspection is totally ignored for lack of qualified personnel. Electronic systems can automatically and accurately monitor driven pile installations and include documentation of certain hammer performance parameters. This paper describes equipment available and routinely in use for automated monitoring of both augercast and driven piles and demonstrates applications on typical construction sites. The paper also discusses benefits and limitations of the alternative NDE tests. KEYWORDS: Augercast Piles, Piles, Installation Monitoring, Pulse Echo Method, Integrity Testing

Jan 1, 1999

By Michael L. Boucher

Copper and nickel sulfides occurring in the Duluth Complex of northern Minnesota were examined at the Bureau of Mines, A microscopic study was undertaken to determine the mineralogy and paragenesis of the ore minerals. Eighty-two samples were taken from one deep diamond drill core located near Babbitt, Minn. Modal analyses are presented for the Duluth Complex rocks and for the are minerals in the major mineralized zone. The major sulfide minerals are chalcopyrite, cubanite, pyrrhotite, troilite, and pentlandite. Results of this investigation suggest that the mineralization is related to the structural features of the enclosing rocks: pores, open fractures, and cavities. The pyrrhotite-troilite-pentlandite assemblage is believed to have formed from an immiscible sulfide melt, probably associated with the troctolitic rocks. Most of it settled to the very porous base of the Duluth Complex, and to the other porous zones near xenoliths; small portions were trapped higher in the section. A later introduction of a copper-rich sulfide melt replaced some of the pyrrhotite-troilite and oxides, and filled in the remaining open spaces and fractures in the Duluth Complex and those of the adjacent footwall rock.

Jan 1, 1975

By Hudson S. B

With a particular electrode configuration, and a particular combination of electrode voltage and roll speed, a relatively small increase in electrode voltage, or a relatively small decrease in roll speed, resultsin a marked improvement in the separation of zircon from ilmenite. In general, fine minerals can be separated using a higher roll speed, or a lower electrode voltage, than is required to separate coarse minerals. The ionizing electrode should be reasonably close to the point at which mineral is fed on to the roll, and nearer to the roll than the non-ionizing electrode. The optimum conditions for the separation of zircon from ilmenite may not apply for the separation of other non-conductors from other conductors.INTRODUCTIONAlthough the high tension separators used in the Australian beach sand industry are efficient, this efficiency has been gained very largely by a process of trial and error, and not by a systematic study of the effects of changes in the operating variables. The optimum roll speed for a particular electrode position and electrode voltage, and the optimum electrode voltage for a particular roll speed and electrode position, can both be determined quite readily. It is not so simple to determine the optimum electrode position for a particular electrode voltage and roll speed. The reason for this is that the electrode used in high tension separators consists of two parts-an ionizing and a non-ionizing electrode respectively. The angular and radial positions of these electrodes, relative to the feed roll and to each other, affect the behaviour of conductors and non-conductors to varying degrees.

Jan 1, 1962

By Sparrow G. J

The effect of polyelectrolyte flocculants on the de-watering of a tailing suspension of very fine clay was investigated.Sedimentation and filtration experiments were carried out in the labqratory to characterise the de-watering properties of the tailing. The results were used to calculate the effect of flocculant additions on the drainage and vaporation components of the de-watering of a clay suspension ponded on to a sand drainage bed.A flocculant increased the drainage rate, but decreased the volume of water that could be removed by drainage leaving more water to be lost by evaporation.The sorptivity values measured in the laboratory were used in the de-watering equation previously established for the tailing to estimate the effect of flocculant additions on the time required to de-water the suspension from 18.2 to 60 per cent solids w/w. The calculated de-watering times were found to increase or decrease depending on the volume of water removed by drainage and the prevailing evaporation rate.

Jan 1, 1980