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By C. Musingwini

An often overlooked factor in the analysis of mine layouts and schedules is technical operating flexibility (or tactical flexibility), mainly due to its nebulous nature. By glossing over technical operating flexibility the resultant mine layouts and schedules maybe suboptimal. The need to incorporate technical operating flexibility into the analysis and comparison of mine layouts and schedules is increasing in importance. The nature of technical operating flexibility is illustrated, previous work on valuing of operating flexibility reviewed, and a proposal made on how technical operating flexibility can be quantified for tabular reef mines by using a platinum reef deposit as a case study. Once technical operating flexibility has been quantified it becomes possible to explore its incorporation into the analysis of mine layouts and schedules and subsequent optimization processes. This paper is a revised version of a paper presented in the Proceedings of the Second International Platinum Conference, ?Platinum Surges Ahead? in 2006. The work described in this paper is part of a current PhD study at the University of the Witwatersrand. Keywords: mine plans, layouts, schedules, technical operating flexibility/tactical flexibility, ore availability.

Jan 1, 2007

By H Matsuno, N Oyama, T Yamamoto, K Nakajima, Y Iwami, N Saito

Recently, the quality of sinter feed ore used in sintering process has deteriorated. In particular, Fe has decreased and gangue component has increased in the sinter feed ore. Increase of gangue is not only the factor to influence sinter qualities, but also the factor to increase coke ratio in the blast furnace operation as the increase of slag ratio. Therefore, to cope with the deterioration of iron ore qualities, studies on alternative iron ore resources and development of its utilisation technology have been required.In that kind of new iron ore resources, authors focus on high-grade magnetite fine. High-grade magnetite fine decreases sinter productivity by the decrease of permeability of sintering bed. Therefore a new study for using large amount of magnetite fine is required. In the past, there are some studies about the effect of mixing ratio and size of magnetite fine on productivity and quality, but there are few studies about magnetite fine segregation in charging.In this research, the melting behaviour and interfacial reaction calcium-ferrite, which has important role as bonding agent among iron ores, melts into hematite substrate and magnetite substrate was studied. As the results, it was defined that upper segregation of high-grade magnetite fine is suitable for productivity of sintered ore. Based on this knowledge, the control method of high-grade magnetite fine segregation by magnetic force at charging was studied with DEM (discrete element method) and its verification experiments for magnetic segregation control was conducted in the laboratory.CITATION:Iwami, Y, Yamamoto, T, Oyama, N, Matsuno, H, Saito, N and Nakajima, K, 2017. Improvement of sinter productivity by control of magnetite ore segregation in sintering bed, in Proceedings Iron Ore 2017, pp 61–68 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By S. Ganguly

Slag samples taken from adjacent to the furnace wall of a submerged arc ferromanganese smelting furnace have been found to contain high concentrations of K2O. To characterize the phase equilibria relevant to these slags experimental studies have been carried out to determine pseudo-ternary sections of the form ?MnO?-CaO-(SiO2+Al2O3) with a fixed Al2O3/SiO2 weight ratio of 0.65 and 6.0 wt% K2O for temperatures in the range 1523-1673 K. In the pseudo-ternary section investigated the primary phase fields are found to be mullite, 3Al2O3?2SiO2; corundum, Al2O3; spinel, MnO?Al2O3; manganosite solid solution, (Mn,Ca)O; dicalcium silicate,2CaO?SiO2; gehlenite 2CaO?Al2O3?SiO2; anorthite CaO?Al2O3?2SiO2; kalsilite KAlSiO4 and leuciteKAlSi2O6. It was found that the presence of K2O in the slag decreases liquidus temperature in the anorthite and gehlenite primary phase fields. The manganosite primary phase field is expanded in the direction of increased (Al2O3+SiO2) and the liquidus temperatures in the manganosite primary phase field are increased significantly with the presence of K2O in the slag.

Jan 1, 2007

This paper discusses the history and development of the system and the benefits that are being gained for Yabulu from Solar Drying. Following the end of mining of the local Greenvale and Brolga nickel deposits, QNI Yabulu Refinery is dependent upon imported ore from over 15 different mines in New Caledonia, Indonesia and the Philippines.

Jan 1, 2003

By Aki Fujii, Hiroshi Dobashi, Mitsuro Matsuda, Yoshinari Kondo

INTRODUCTION The Metropolitan Expressway Central Circular Route with a total length of approximately 47 km is located outside the Inner Circular Route of Tokyo (at a radius of approximately 8 km from the city center). Sections with a length of approximately26 km, slightly less than 60% of the total length, on the east and north sides are in ser-vice. Completing the Central Circular Route (Figure 1) is expected to enable through traffic concentrated at the city center to get around, and to form a well balanced trans-port network, which will alleviate traffic congestion considerably. The Central Circular Shinjuku Route, a section with a length of approximately 11 km on the west side, is now being constructed at a fast pace. The route is being built mainly by the shield tunneling method to carry out work smoothly under a trunk highway carrying heavy traffic and to reduce adverse effects of tunneling work on residents in the neighborhood. Shield tunnels have recently been becoming longer and deeper, and no secondary linings have been used in an increasing number of cases because of the over-crowding of cities or the reduction of budgets for public works. Economical, durable and high-quality segments have been required for linings of shield tunnels. Segments are made of concrete, steel, cast iron or combination thereof. Concrete segments are generally used in shield tunnels of medium to large diameter. Concrete segments are highly durable and resistant to compression, so they are highly resistant to earth pres-sure, water pressure and jack thrust. They are, however, heavy and have low tensile strength, so they are brittle and their corners are likely to spall. Concrete segments should therefore be handled carefully.[1] The authors have developed a steel fiber reinforced highly flowable concrete segment (referred as SFRC segment) that overcomes the weaknesses of concrete segments[2] to construct economical, durable and high-quality linings. SFRC segments have been applied to outbound sections SJ51 through SJ53 of the Central Circular Shinjuku Route. Unlike conventional concrete segments (referred as conventional RC segments), SFRC segments are made of steel fiber reinforced self-compacting highly flowable concrete. SFRC segments require less reinforcing bars than conventional RC segments because steel fibers are expected to work as reinforcements. Steel fiber reinforced concrete is a composite material that overcomes the brittleness of plain concrete, and has higher resistance to bending, tension and shear than

Jan 1, 2007

By C. T. Aimone-Martin, B. M. Meins

This paper compares response of large urban structures to small charge weight, ultra-high frequency rock blast excitation from contiguous excavation to that of houses to more distant, larger charge weight blasts. Time correlated responses were measured for both structures at the corners, top and bottom of the structures as well as in the foundation rock below the bottom. The comparison allowed the following conclusions: Close-in blasting with direct rock to building wave transmission imposes short wave length excitation which fails to excite the large, massive structures synchronously whereas the more distant blasts do synchronously excite houses. The larger urban structures respond predominantly in wave transmission mode where there is a noticeable difference in time, frequency, phase and amplitude of motions measured at the bottom and top corners of the structure. Excitation motions along the base of the larger urban structures also differs in time, frequency, phase and ampli-tude. The short wave length of the excitation motions leads to attenuation of the peak particle veloc-ity along the base. Ultra-high excitation frequencies, which are much higher than the expected struc-tural natural frequencies, lead to deamplification for all events for the large urban structures.

Jan 1, 2018

By E. L. Garton

[Analyses of may crude oils produced in Louisiana are included in reports that t have boon published by the Bureau of Mines. The first report, giving, analyse of 6 Louisiana crude oils, was 3 published in 1921 and this was followed a year later by Report of Investigations 2416,4/ giving 7 additional analyses. The eleven most important of these analyses were incorporated in Bulletin 291.5/ issued in 1928 In 1934 analyses of 26 crude oils produced in southern Louisiana were published.6/ The percent report presents analyses of 72 additional samples of crude oil from 45 fields in 23 parishes In Louisiana.]

Jan 1, 1939

By Liang Sha

In this study, adsorption of copper by chemically modified orange peel was investigated. A conspicuous change occurs in the surface morphology of the biomass due to modification, which is depicted by SEM images. Equilibrium isotherms and kinetics were obtained and the effects of various factors, including solution pH, contact time, initial metal ions concentration and temperature, were studied by batch experiments. Kinetics was found to be best-fit pseudosecond- order equations. Equilibrium was better described by Langermuir isotherms rather than Freudlich isotherms. At 25?, pH5.30, the maximum adsorption capacity was 70.67mg?g-1 . With increase of temperature, adsorption efficiency decreased. The biosorbent was suitable for repeated use for more than five cycles.

Jan 1, 2009

By N van Aarde, B A. Moore, S van der Merwe

Frequently materials handling operations are compromised by transfer chute problems ranging from high wear rates, blockages and ineffective loading of the downstream conveyor. This paper will present the design flow implemented to overcome problems in two case studies utilising discrete element modelling incorporating material characterisation.Material testing is relevant in achieving a valid discrete element method (DEM) simulation model and subsequently a valuable design tool for transfer chute assessment and design. It is well recognised that in the current growth and demand for mineral resources, leading to ever increasing conveyor capacities associated with export terminals and mineral processing facilities that transfer chutes are a key focus point. The successful performance of the transfer chute is also dependent on operating with a ærobust rangeÆ of material flowability and handling characteristics. This requirement is crucial in accommodating mineral ores from developing resources, which are often more friable and stickier than in past decades.This paper will include details of chute installations associated with iron ore and coking coal, from the DEM simulations through to the performance of the installed and commissioned plant.CITATION:Moore, B A, van der Merwe, S and van Aarde, N, 2013. Implementation of advanced transfer chute designs, in Proceedings Iron Ore 2013 , pp 445-450 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

The pressure of low commodity prices forced the design process for the second lift of Northparkes E26 Mine to adopt a continuous improvement philosophy. The emphasis was to minimise capital expenditure while still maintaining the excellent low operating costs achieved on Lift 1. Although the first block cave lift at Northparkes is the most productive underground mine in the world and is held up as a benchmark for the use of technology in mining, areas for improvement were identified. Every area was critically assessed and investigated for the possible application of new techniques and technologies. Key learnings from the construction and production phases of Lift 1 were captured, documented and used as the starting point for the Lift 2 design. This paper shows how and why the design parameters initially used onLift 1 were changed to become the current E26 Lift 2 developmentproposal. The main differences between the two block caves arehighlighted. The alternative techniques and equipment that wereconsidered are also discussed. * Originally published in the Proceedings of MassMin 2000,published by The AusIMM.

Jan 1, 2001

By G. W. Elger

This report describes pilot-plant studies and an economic evaluation of a process developed by the Federal Bureau of Mines, Albany Metallurgy Research Center, to produce synthetic rutile from a rock-type ilmenite concentrate. In this process, ilmenite blended with coke and lime is smelted in an electric arc furnace to separate most of the iron as salable pig iron and to form a titania-enriched slag of low iron content, which is treated with oxygen and titanium pyrophosphate. The titanium oxides are converted to crystalline rutile; the phosphate glass contains most of the associated impurities. The treated slag is ground and leached with sulfuric acid to liberate rutile crystals, which are concentrated by physical methods. In pilot testing conducted to obtain data for a cost estimation, a synthesized product containing about 88 wt-pct TiO2 and less than 2 pct FeO was extracted from a rock-type ilmenite concentrate containing about 45 wt-pct TiO2. The estimated fixed capital cost (on a mid-1975 basis) of a plant producing 500 tpd of synthetic rutile is $28,290,100. Based on 330 operating days per year, the estimated operating cost for this process is $351 per ton of synthetic rutile. The estimated selling price of synthetic rutile made from rock-type ilmenite is $344 per ton, based on a credit of $160 per ton of pig iron and a 20 pct interest rate of return on investment after taxes.

Jan 1, 1976

By Michael Rehbock-Sander

The Gotthard Base Tunnel (GBT) is 57 km (35 miles) long and consists of two par-allel single-track tubes with an ex-cavation diameter ranging from 8.8 to 9.5 m (28.8 to 31.2 ft). These are interlinked by cross-passages every 312 m (1,000 ft). Two multifunction stations (MFS) are located in the sections Sedrun and Faido, at one-third and two-thirds of the entire tunnel length (Fig. 1). These will be used for the diversion of trains to the other main tube via tunnel crossovers, for the housing of tech-nical infrastructure and equipment and for potential emergency stops. To reduce construction time, the GBT was divided into five sections and was excavated from several sites simultaneously. The tunnel was excavated from the two portals, Erstfeld in the north and Bodio in the south, and also from three intermediate attacks, with their corresponding access tunnels, in Amsteg and Faido and two vertical 800-m (2,624-ft) deep shafts in Sedrun.

Jan 1, 2012

By Carlos Henrique Silveira Aguiar

O tubo formador de espiras é uma guia que está localizada no Laying Head, especificado de acordo com a norma ASTM 335P22, e tem por função conformar o fio-máquina na forma de espiras sobre o transportador Stelmor. O Laying Head gira continuamente, durante a operação normal, sendo que a cada revolução do tubo, uma espira é produzida, cujo diâmetro é determinado pelo raio final do tubo e pela velocidade do Laying Head, em relação à velocidade do Laminador. Estes tubos, durante a laminação dos aços BEXX, sofrem um desgaste acentuado, que é provocado pela carepa formada durante a passagem do fio máquina pelas caixas d’água, durante o processo de resfriamento. Desta forma, torna-se necessário trocá-los a cada 200t laminadas do referido aço, com tempo estimado de 30 minutos de parada. Além disso, há um desgaste físico acentuado na atividade de troca dos tubos, que coloca em risco a segurança dos funcionários. Outro efeito indesejável relaciona-se com o risco de ocorrência de sucata de linha, provocada pelo rasgamento do tubo, quando são fornecidos tubos cuja composição química se apresenta no limite inferior de especificação. Há programa de laminação que exige até 6 trocas diárias de tubo. Com a proposta de se incrementar a tonelagem laminada por canal dos discos de laminação do Bloco No Twist, tornou-se necessário desenvolver um tubo com insertos de metal duro, com vistas a aumentar a vida útil dos mesmos, como também a produtividade do Laminador 2.

Jul 30, 2018

By Alfred V. C. Meyer

A Blastcorder4 was calibrated on the Bureau of Mines shaking table in the frequency range of 12 to 40 c.p.s. and in the amplitude range' of 0.25 to 1.0 g. The results of this calibration study show that in the frequency range of 12 to 30 c.p.s. the average accuracy of the Blastcorder is approximately ± 0.1 g.

Jan 1, 1962

By Caithness SJ, Heape JMT

Following the discovery by CRA of gold at Mt Kare, and the subsequent 1988-90 gold rush, mechanised mining of the alluvial resource is now being carried by a company jointly owned by CRA (51%) and landowners of the area (49%). Mining is currently being carried out using small gravity processing plants fed by hydraulic excavators. Use of hydraulic mining techniques will be limited to over- coming difficulties related to the high clay content of the material and the soft nature of the bedrock. Current resource estimates suggest that the alluvials will have a mining life of three to four years. During this time, exploration of the hydrothermal gold mineralisation at Mt Kare will be carried out by a wholly-owned company of CRA. It is hoped that this will lead to establishment of an economic primary gold resource.

Jan 1, 1991

By Oliver Bowles

Whiting or Paris white is a fine-grained preparation of calcium carbonate having a wide variety of uses. Until recent years it was prepared almost exclusively from certain north European chalks. With the curtailment of imports of European chalk during the World War of 1914-18, however, finely ground limestone, of domestic origin was used more extensively to satisfy the American demand.

Jan 1, 1942

By T. Gerritsen, R. C. Delgado, J. Janzen, E. R. Veloza

The paper describes the components of an Integrated Furnace Control system for covered-arc (shielded arc) smelting with results from the recently started 75 MW Cerro Matoso Line 2 Furnace. The paper starts with a review of the mechanisms of power and feed input and heat losses in the shielded-arc smelting process, and describes how the details of the control system are tailored to the process. The control modules of a covered-arc smelting furnace are described including measured results and screen captures. This paper focuses on Integrated Furnace Controls tailored to shielded-arc smelting, but similar approaches have been recently applied to other furnace processes including immersed-arc smelting.

Jan 1, 2004

By P J. B Fransen

Several spatially and/or temporally distinct phases of epithermal activity can be recognised in the Horohoro-Matahana Basin area of the Taupo Volcanic Zone. In the northern Matahana Basin a 140 - 350 ka age range is proposed for mineralised debris flow clasts and related (?) epithermal  mineralisation intersected in a recent drillhole. To the east, a ca. 40 - 50 ka age range is suggested for epithermal activity in the Waikaukau alteration zone which was focused along the Guthrie Fault. Hydrothermal explosion breccias occur over 13 km within the Guthrie Graben, and are probably sourced from vents in the south. Assuming a common origin, these breccias are constrained to a 45 - 50 ka age range. Within the Horohoro hydrothermal system (around the present hot spring), older (15 - 50 ka) and younger (0 - 15 ka) features can be distinguished.

Jan 1, 1991

By P. H. S. W. Kulatilake

To exploit an underground mine effectively and safely, it is important to have a good understanding of the geotechnical behavior around underground excavations made in the mine. The aim of this study was to investigate the geotechnical behavior around a tunnel excavated in a metal mine in China at the three-dimensional level. Using the information available on lithology, geological structures, in-situ stress measurements, physical and mechanical properties of intact rock, discontinuities and interfaces between different rocks, a three-dimensional numerical model was built by using the 3DEC software to simulate a tunnel excavation under a high in-situ stress condition. Effect of the discontinuity network, possible intact rock and discontinuity parameter variability, representation of rock masses as discontinuum or continuum material and rock support system on the deformation, stress, failure zone and stability around the tunnel was investigated. A very good agreement was obtained between the collected field deformation monitoring results and the results of the conducted numerical stress analyses.

Jan 1, 2012

By Meghan McGrath

Third generation advance high strength steels with microstructures of acicular ferrite and retained austenite were investigated and meet mechanical property goals. A good combination of strength and ductility were achieved with duplex ferrite and austenite microstructures where cementite formation was suppressed. Transformation induced plasticity (TRIP) behavior produced rapid work hardening. The mechanical properties of two hot-rolled steels with duplex microstructures were compared and had the following compositions: (1) Fe-0.14C-13.87Mn-1.42Si-3.51Al; and (2) Fe-0.06C-14.2Mn-1.85Si-2.38Al. These steels were cast, homogenized, and hot rolled at 900ºC to obtain a refined microstructure with ultimate tensile strengths and elongations to failure of 865 MPa and 39% and 1,217 MPa and 28%, respectively. The amount of metastable austenite in both compositions decreased after tensile testing from 58% and 28% to 6% and 0%, respectively. Microstructures were characterized using optical microscopy, scanning electron microscopy (SEM), and x-ray diffraction.

Jan 1, 2010