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By M. F. Dlamini

The hydrodynamics of a hydrocyclone present a complex internal flow structure, the numerical simulation of which remains a non-trivial task. We report on three-dimensional water-only computational fluid dynamics (CFD) hydrocyclone flow field predictions and highlight some of the issues concerned with the development of a CFD model incorporating an air core. The potential for the application of CFD as a hydrocyclone design tool is also discussed. Physically realistic velocity profile predictions were obtained, which challenge the classical account of the hydrocyclone radial particle classification mechanism. A pressure field distribution consistent with literature reports was also predicted. Keywords: hydrocyclone, computational fluid dynamics (CFD),classification mechanism

Jan 1, 2005

By A. J. Williams

"Conventional base metal milling practice normally consists of crushing, grinding and cyclone classification followed by flotation. It is the authors' belief that the commencement of flotation after cyclone classification leads to inferior metallurgical results and that implementation of flotation of grinding mill discharges can result in increased recovery due to reduced overgrinding, reduced activation of contaminating minerals and improved dewatering circuit results due to the production of coarser concentrates.The concept of recovering minerals from the discharge of grinding mills is not new! Gold concentrators have utilized jigs and flotation cells while iron ore plants have employed magnetic separators to recover gold and magnetite respectively from the discharge of grinding mills. More recently, a Reichert cone has been used to recover sulphide and oxide base metal minerals from screened rod mill discharge. 1To the authors' knowledge, the first application of flotation of base metal minerals from the discharge of a production plant grinding mill was at the Lake Dufault concentrator of Corpor'1tion Falcon bridge Copper. Located 10 miles north of Noranda, Quebec the Lake Dufault concentrator commenced operations in August, 1964.The installation of flot11tion cells in the Lake Dufault grinding circuit proved so successful that an identical system was installed in the Manibridge concentrator of Falconbridge Nickel Mines Limited. Located 90 miles southwest of Thompson, Manitoba the Mamibridge concentrator commenced operations in June, 1971 and due to exhaustion of economic ore reserves discontinued production in May 1977."

Jan 1, 1984

By S M. Aminossadati, R Bagherpour, F Hasheminasab

Mine ventilation is an essential part of underground mining operations used to provide fresh and cool air, as well as to dilute and remove contaminants from the work environment. This paper presents an overview of the ventilation and gas management systems in one of the underground coalmines in Iran: Parvadeh_1 mine. The mine is located in the Tabas coalfield in the South Khorasan province. It is the only fully mechanised mine in Iran utilising the longwall retreat technique. The mine produces 1.1 to 1.3 Mt of coking coal annually. The mine ventilation system currently utilises two 630 kW exhaust surface fans. The gas management system includes surface to in seam (SIS) predrainage boreholes. The underground mine is equipped with an underground gas reticulation pipeline that is connected to a surface plant for the production of methane gas. This study shows that the ventilation and gas management systems of the Parvadeh_1 mine are in line with the standards of Australian underground mines.CITATION:Hasheminasab, F, Aminossadati, S M and Bagherpour, R, 2017. An overview of ventilation and gas management systems in an underground coalmine in Iran, in Proceedings Australian Mine Vent Conference 2017, pp 41–46 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017

By Jesse R. Jacobson

A large casino complex in Cherokee, North Carolina recently underwent a $633 million expansion that involved substantial foundation challenges. The site is located in a valley on the southern edge of the Great Smoky Mountains National Park, where subsurface conditions typically consist of varying thicknesses of fill overlying alluvium, residuum, partially weathered rock and rock. The fill and alluvium contain cobbles and boulders as large as several feet in diameter. The residuum and partially weathered rock are very thick in some areas, and the depth at which consistently high quality rock is encountered is highly variable. To reduce the foundation costs for the expansion, continuous flight auger (CFA) piles were proposed in lieu of micropiles. CFA piles are not generally used in this geologic environment and concerns regarding their selection included: (1) an uncertainty that CFA piles could be successfully constructed given the difficult conditions and (2) a lack of regional data regarding unit resistance values and load transfer characteristics. To address these concerns, a design-phase test program was undertaken to evaluate pile constructability, develop an understanding of the load transfer behavior, and establish the required pile lengths. The program included soil test borings, shear wave velocity measurements, timed auger probes, instrumented pile load tests and observation of exhumed piles. It was demonstrated that CFA piles could be advanced through the fill, cobble/boulder-laden alluvium, residuum and into the partially weathered rock, albeit with some limitations. Under axial loading, the pile response was very stiff and relatively high unit resistance values were measured. Pile instrumentation allowed for the evaluation and use of design pile lengths shorter than that tested, and the overall reduction in pile lengths yielded a 40 percent reduction in foundation cost. In general, CFA piles were determined to be a suitable, economical foundation alternative.

Jan 1, 2011

By S. J. Schatzel

In order to better understand the effects of longwall mining on the methane reservoir overlying the panel, the National Institute for Occupational Safety and Health/Pittsburgh Research Laboratory (NIOSH/PRL) designed and implemented a vertical borehole monitoring experiment (BME) on an active longwall panel. The mine operates in the Pittsburgh Coalbed in Greene County, Pennsylvania. The BME site was located away from either end of the panel to avoid mechanical influences caused by the draping of overburden in this region and was positioned at the same distance from the tailgate gateroad as the mine?s gob gas venthole sites. The borehole drilling depths and monitoring intervals were chosen to address a different stratigraphic zone in each of the three planned holes. The monitoring boreholes were positioned perpendicular to face advance using a close spacing pattern of about 15 m (50 ft) between collars. Boreholes were instrumented downhole and on the surface for various measurements. It was observed from the field data that the gob gas venthole fracture network formed 24-46 m (80-150 ft) ahead of the mining face. Overburden permeability?s within the same test zones increased 100 to 500 times following undermining. The borehole test interval within the fractured rock responded to overburden gas pressure while the test interval in the caved zone responded to mine ventilation conditions. Eight months after the boreholes were undermined, slug testing indicated permeabilities had increased further in the fractured rock zone. Measurements of surface movement indicate that the permeability development observed in the boreholes is a product of vertical subsidence without lateral movement within the tensional rock mechanics zone on a supercritical longwall panel. Results from this study suggest that maximum permeability in the longwall panel overburden is achieved 58 to 190 m (190 to 620 ft) behind the longwall following maximum compaction of the overburden.

Jan 1, 2009

By Donald A. Bruce

The construction of major structures in karstic limestone terrains poses difficult problems to designer and contractor alike. This reflects the inherent variability of such conditions, and also the significant impacts caused by the construction processes themselves. Three case histories are provided of recent projects in the United States: the sealing of a major inflow into a quarry, the improvement of a highly loaded bridge pier foundation, and the installation of high capacity micropiles. Emphasis is placed on problem assessment and execution verification.

Jan 1, 2002

Relatively few longwall mines in the U.S. operate under multiple seam conditions where the two seams are less than 200 ft apart. This paper describes the experience of six that do. These operations are located in PA, WV and UT, and include examples of both undermining and overmining. Some operate above or beneath their own workings, others are in historic mining districts and must contend with abandoned mines that are decades old. The lessons that these mines have learned cover a broad range of topics, including: • Whether to stack gateroads or place them under old gob areas; • How to size pillars and select artificial support to cross longwall stop lines; • How to use yield pillars to minimize multiple seam stresses and coal bump potential, and; • When to anticipate the creation of pathways for gas, water, or oxygen between current and abandoned gobs.

By D. Xie, S. Sun

An overview of recent development of CSIRO?s Multi-Phase reaction models will be presented with examples comparing the calculated physico-chemical properties of metallurgical slags with the existing experimental data. The paper will also outline the development of a kinetically based model for molten bath reactors and its application to submerged combustion of coal in a slag bath as well as the reaction between the slag and injected coal particles. The plume model combines established models for the combustion of pulverized fuel with models for the growth and rise of bubbles from a lance or tuyere. This model predicts the extent of de-volatilization and combustion of the coal in the plume, the utilization of oxygen and the exchange rate of oxygen between the gas and the bath as well as the heat transfer rate between the gas bubbles and the bath. The slag reduction model brings together the recently measured rate data and fundamental understanding of the kinetics of CO-CO2reaction with iron oxide containing slags and predicts the changes resulting from injection of coal particles into molten slags. The top-space model covers reactions between gases and molten droplets in the post-combustion zone, where heat and mass transfer between phases results in higher utilization of the fuel values in the partly oxidized gases and transfer of heat to the molten bath. Keywords: Phase equilibria, viscosity, electrical conductivity, slags, kinetics, reaction rate.

Jan 1, 2004

By M. Nete

Qualitative analysis of three mineral samples from northern Mozambique was accomplished by X-ray diffraction (XRD), microscopy, scintillation, and magnetic determination. Chemical characterization was accomplished using ICP-OES and pressed powder XRF after dissolution using microwave-assisted digestion and flux fusion. The samples consisted of a mixture of minerals with tantalite as the major component, with minor amounts of microlite, quartz, mica, accessory garnet, and tourmaline. Incomplete dissolution was obtained using microwave digestion, with maximum recoveries of 90.25 ± 0.06% and 88.90 ± 0.04% for Nb2O5 and Ta2O5 respectively. Complete dissolution using Li2B4O7 resulted in recoveries of 98.5 ±0.2% Nb2O5 and 100.4 ± 0.3% Ta2O5.

Jan 1, 2012

By B. J. Arnold, N. Terblanche

The features of the ‘Turbo’ froth flotation column will be discussed, including the double aeration system that improves flotation yield while not sacrificing grade, the internal launder system, and the unique feed/tailings sump that evens out flow to the flotation column preventing upset conditions. Results from various test programs and installations will be presented.

Jan 1, 2001

By Francis Kendorski

The Skyline #3 Mine of Canyon Fuel Company in Utah was planning longwall mine development adjacent to and downdip of older mine workings known to be flooded. Barrier pillar geometries and widths were proposed by mining company personnel. Hydraulic conductivity testing suggested that the general characteristics of the local coal seam, dikes, and faults are only weakly conductive and that leakage through the barriers, if any, would be minor. The mechanical performance of the proposed barrier pillar design was evaluated according to (1) published empirical design methods and (2) numerical stress modeling. Comparison of the proposed design, with the range of barrier widths derived from the empirical methods, served as a first-order check on the adequacy of the proposed design. Numerical modeling was used to evaluate conditions site-specific to the Skyline #3 Mine and barrier geometry. Models were developed to quantify the relationship between barrier width and the abutment stresses onto the future workings. The models were also used to estimate the stress distribution within the barrier pillars. The hydraulic performance of the proposed barrier pillar design was evaluated according to (1) published empirical design methods for hydraulic impoundments, (2) empirical method estimates of seepage through coal barrier pillars, (3) numerical hydrogeologic flow modeling, and (4) numerical strain modeling. Using the techniques described above, and based on relevant industry experience, underground observations, knowledge of local geologic conditions, hydrogeologic measurements, and analytical results, the level of geomechanical risk associated with the barrier design as proposed was considered low and the level of hydraulic risk was considered moderate. The largest uncertainty that remained was the possibility that unfavorable geologic structures, such as faults and dikes, would act as conduits for leakage of impounded water into the new workings. Although the study indicated only minor steady-state leakage would occur through a small number of known structures, the presence and full leakage potential of threatening structures in the barrier could not be reliably known until the barrier was mined. One longwall panel has been completed adjacent to the barrier with no evidence of water flow even in fractured zones. Thus, as predicted by the modeling and analysis, it appears that abutment stresses imparted on the barrier during mining did not substantially alter the natural hydrogeologic characteristics, or leakage potential, of the barrier. The longwall coal mine water-barrier pillar design and performance are considered a success.

Jan 1, 2007

By S. E. Cook

This article uses the case of the Royal Bafokeng Nation to argue that royalties and dividends from mineral resources, if managed well, can provide direct benefits to the surrounding community even while the state collects its share of mining revenues through taxation. The key to this model is the effective management of the resource income flowing into community coffers. Where some of this income may fund urgent interventions in the community, a portion of the income can also be used to establish an intergenerational wealth fund to meet the needs of future generations. As a depleting resource, minerals like gold and platinum are not a sustainable source of income, and must be replaced over time by more regenerative income streams. These strategies and dynamics are manifest in the Royal Bafokeng Nation?s status as both community and quasi-municipality, a labour hosting and a labour sending community, a mine operator and a mine owner. The Royal Bafokeng Nation also owns one of South Africa?s largest community-based investment companies, which channels revenue derived from platinum deposits into a broad investment portfolio that in turn funds an aggressive social development program for 150,000 people living in twenty-nine rural villages.

Jan 1, 2013

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Jan 1, 1994

By P. J. Rowsell, M. D. Waller

Paper presented at a meeting on: Artificial intelligence in the minerals sector, held in Nottingham, UK, 20 April 1993. The applications of artificial intelligence systems in the upstream petroleum industry are reviewed. Particular emphasis is placed on current and potential applications in drilling engineering. Several recent advances in drilling technology have led to a large increase in the quality and volume of data available. This combined with the escalating cost, particularly of off-shore operations, is testing the traditional reliance on the skill and judgement of rig operators. AI systems offer enormous scope in enhancing and aiding the performance of these operations

Apr 1, 1994

By S. McGinn

The Brunswick Mine Diesel Particulate Filter Study was one of several research projects initiated by the Diesel Emissions Evaluation Program (DEEP). The study was carried out at Noranda?s Brunswick Mine in Bathurst, New Brunswick by Noranda Technology Centre and Brunswick Mine personnel with the collaboration of Natural Resources Canada - Canada Centre for Minerals and Energy Technology (CANMET), National Institute of Occupational Safety and Health (NIOSH), Andreas Mayer of VERT, and diesel particulate filter (DPF) system suppliers. The study began in early 2000. Field evaluations continued for 20 months. The final report?authored by Sean McGinn?was submitted to DEEP in the Autumn of 2003.

Jan 1, 2004

By John C. Machisak

STATISTICAL data on injuries and employment pertinent to metal mines and to their mills, and/or processing plants are presented in this Information Circular for the calendar year 1960. The information pertains to metal mines, as well as ore-dressing plants and primary nonferrous smelters, refineries and reduction plants, and their auxiliary works. These data are voluntarily submitted annually to the Bureau of Mines by the operators, and contribute greatly toward the promotion of safety in the mineral industries. The data presented are classified according to the principal mineral produced and include information on copper, iron, lead-zinc, gold-silver lode, gold placer, uranium-vanadium and miscellaneous metals. A breakdown of miscellaneous metals by commodities is shown in table 19, page 41. The data also relate to workers engaged in production, exploration, development, construction, and maintenance and repair work, as well as supervisory personnel and office- workers at the mine or plant site. Injury and employment data at metal mines and metallurgical plants in the United States for 1960 are shown under the following general sections:

Jan 1, 1963

By G. Ahnell

Throughout portions of four (4) heavily mined Appalachian states subdivided by the Mine Safety and Health Administration (MSHA) as: District 3 -Northern West Virginia and Maryland; District'" -Southern West Virginia; District 5 -Virginia; and District 6 -Eastern Kentucky, active coal mine waste embankments associated with mechanical and/or chemical coal processing facilities of various levels of coal preparation were inventoried. For each site plant specifications, disposal techniques, embankments' characteristics, and coal source data were accumulated. Mapping at 1: 24, 000 and 1: 250,000 scale and Disposal Site Characterization forms were developed to present the findings. Associated abandoned surface and underground openings near each site were also indicated as well as locational data for each site and the areas environmental conditions - temperature, precipitation and vegetation types. A state-of-the-art review of coal preparation, waste disposal, and alternative uses of coal waste is also included.

Jan 1, 1982

By L. Cheng

This report presents the results of a Bureau of Mines laboratory investigation of the effect of water sprays in reducing respirable dust that escaped the face area of a full-scale wooden model of a mine en-try containing a wooden model of a ripper-type continuous mining machine and exhaust brattice. Areas examined were (a) the general effectiveness of a low-pressure water spray system mounted on top of the mining machine boom, a high-pressure spray system mounted under the boom, and the combined top-and bottom-spray systems, and (b) the effect of these three spray systems on the capture of coal dust particles of different sizes. Dust was injected into a sump cavity at the face. Airborne respirable dust concentration was mea-sured behind the brattice with a personal sampler and cyclone, and particle size distribution was mea-sured with a cascade impactor. When used alone, the top-spray system captured about 55 pct of the respirable dust in the face area and the bottom-spray system captured 60 pct; the capture efficiency of each system is decreased when they are used simultaneously. From a mass-concentration viewpoint, each spray system preferentially captures larger dust particles.

Jan 1, 1988

By C. Kloppers

The aim of this investigation was to reduce the cost of primary steel de-oxidation by substitution of aluminium primary de-oxidation with a practice that uses carbon. The cost of carbon is four times lower than that of aluminium. The application of carbon would directly result in raw material cost savings. Investigations were conducted at Iscor?s Newcastle steel plant on various steel grades. Specific production aspects were emphasized to ensure that the cost savings accrued would not create secondary expenses. These production aspects entailed: ?Yields on de-oxidation elements ?De-oxidation capabilities ?Alloying yields (Mn and Si) ?Carbon-pickup ?Nitrogen-pickup ?Temperature loss during tap ?Steel cleanliness ?Slag morphology. This project proved that carbon de-oxidation, apart from reducing de-oxidation raw material cost due to cheaper raw materials being used and lower consumption rates, resulted in steel that is cleaner and has lower nitrogen concentrations. Carbon primary de-oxidation has been implemented at Iscor?s Newcastle plant on a large range of steel grades, ranging from ultra-high carbon (> 0.60% C) to ultra-low carbon (< 0.03% C) grades. A net saving of between R100 000 and R200 000 per month was achieved.

Jan 1, 2001

By Lance A. Roberts

Micropiles are commonly utilized for applications other than foundation retrofit. In bridges, for example, micropiles can serve as the permanent foundation elements or can be used in temporary support applications. In this paper, a case study on the use of micropiles for the 18th Street Expressway Bridge rehabilitation/repair project in Kansas City, Kansas is presented. In the project, micropiles were utilized for support of six temporary jacking structures, which allowed the bridge to be lifted while repairs were completed. A group of six micropiles was required to support each jacking structure. The required compressive service load per micropile was approximately 300 kips (1300 kN) and the settlement of the micropiles under the service load was to be limited to 0.5 in. (12.7 mm). Two field compression tests were conducted as part of the project. The field load test data was integrated within a soil-structure interaction capacity approach in order to analyze and permit the shortening of the design bond length for the production micropiles.

Jan 1, 2009