Search Documents

By M E. Pierce, T V. Garza-Cruz

Rock mass strength and brittleness generally have a significant impact on both cavability and fragmentation. Variability in these properties across a panel or block footprint is of particular interest because stronger units have the potential to significantly impact cave shape. This paper describes how FLAC3D™ was used to examine the impact of variability in rock mass properties on predicted cave performance to aid in assessing potential risks associated with the proposed design.A case study orebody was subdivided into a number of domains to reflect the heterogeneity of the rock mass at the scale of a proposed inclined cave. The results suggest that the presence of stronger units has the potential to impact cave shape significantly in the southern half of the cave footprint and could increase the potential for cave stalling at shallow depths. If this unit is stronger and less brittle than expected, an overhang is predicted to develop in the southern half of the inclined cave at depth. The effective hydraulic radius is significantly reduced due to the overhang in the south, and the cave could eventually stall at shallower depths in the north.CITATION:Garza-Cruz, T V and Pierce, M E, 2016. Impact of rock mass strength variability on caving, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 359–368 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

If you have problems or questions relating to the installation of this disc, please either telephone Document Transformation Technologies at (+27 12) 667 2074, or e-mail: nigel@doctech.co.za Si vous avez des problèmes relatifs àl?installation de ce disque, veuillez appeler Document Transformation Technologies au (+27 12) 667 2074, ou nous écrire par courrier électronique: nigel@doctech.co.za Produced by: / Produitpar:Document Transformation TechnologiesP O Box 560 ?Irene ?0062 ?South Africa.Tel: (012) 667 2074; Fax: (012) 667 2766; International Code (+27 12) e-mail: doctech@doctech.com website: http://www.doctech.co.za

Jan 1, 2004

By McDonald G. G

In the deformation of a metal or a single-phase alloy all the crystals composing the metal after their shape in a similar manner as the metal in bulk and to about· the same extent. This is not the case in an alloy consisting of two phases of different resistance to plastic deformation. In such an alloy the two phases take part in the deformation approximately in inverse proportion to their hardness, at least at the beginning of the deformation. (1) The hardness difference becomes less in the course of the deformation and thereby the deformation more equal. The phenomena occurring during cold-rolling of some two-phase alloys have been investigated by H. Unckel who made statistical grain measurements of the degree of deformation of the two phases after various reductions by rolling and also microscopical observations of the flow in the neighbourhood of the grain boundaries. Because of the different relative flow of the two phases, the normal flow is disturbed in the vicinity of their boundaries, and some additional plastic flow must take place in these regions, the disturbance being levelled out at some distance from the boundary. The deformation of the two phases present simultaneously in the material should thus be different from that of each phase separately. The investigation of theimportance and the effects of this interaction of crystals of different phases is the subject of this paper.The deformation of crystals occurs as a gliding of crystal layers following crystallographic laws. In consequence of this slip the crystals composing the material tend to assume a common orientation, i.e. some crystallographic axes tend to become parallel to each other in all the crystals. The type of this preferred orientation depends on the type of the crystal and the working process. Any change in the mechanism of deformation results, therefore, in a change in the preferred orientation. Such a change in kind and degree of preferred orientation will, therefore, also occur if the interaction of crystals in a two-phase alloy gives rise to a mechanism of deformation different from that in the free phases.The present paper describes a study of the preferred orientation, the microstructure and hardness in wires of brass drawn to various extents.The development of preferred orientations in the two phases with increasing reduction was followed up in various layers of the wire.EXPERIMENTAL DETAILSThe experiments were carried out with a commercial 5 S.W.G. wire (0,212 in. diameter) containing: 62·7% Cu, 37·3% Zn, very faint traces...

Jan 1, 1941

By William B. Plank

IN this paper are presented the results of a complete statistical survey of the enrolment, courses and degrees, and the employment situation of recent graduates in all of the 46 institutions in the United States, including Alaska, and four of the six schools in Canada that grant degrees in mineral technology. The data were collected by the writer by means of a questionnaire in December, 1933, to which all the institutions, except one, replied. Included also are data of a similar study made by the writer in May, 1933, for the S. P. E. E. summer session of mining and metallurgical teachers at the University of Wisconsin and published in the Journal of Engineering Education for December. 1933. Some of the data of a paper of the writer's entitled, "The Trend of Mineral Engineering Student Enrolment in the United States," read at the A. I. M. E. meeting on Feb. 16. 1931, are given for comparison. Acknowledgment is made to all the administrative officers of the institutions who took the time from their busy lives to supply the in- formation asked for. Their fine cooperation has alone made possible these two surveys with a completeness of detail never before attempted

Jan 1, 1934

By M. K. Sichone

Anglo Platinum?s Waterval smelting complex based in South Africa operates the Anglo Converting Process (ACP) that produces SO2 offgas. This SO2 offgas is treated in a double-contact, double-absorption acid plant allowing for conversion efficiencies higher than 99.90 %. The catalytic converter used in the acid plant to convert the SO2 to SO3 is a 4-bed reactor loaded with a combination of cesium-promoted and conventional vanadium pentoxide catalysts. In June 2008 there was a shutdown, in which one of the main activities was to screen the catalyst. Before this shutdown, the operator would control the converter pass temperatures manually, via the SCADA, especially during plant start-ups after which some of the automatic temperature controllers were used. After the shutdown, the control philosophy was revisited and all temperature controllers were put on auto mode during plant start up. Furthermore the set points of the pass inlet temperatures were reduced to maximize conversion in the first two passes. The result has been a reduction of SO2 emissions, from a daily average of 50 ? 70 ppm to as low as 20 ppm for similar sulphur dioxide and oxygen concentrations. Further work has been done to maintain high bed temperatures in the third and fourth passes at low SO2 strengths by splitting the gas stream between pass 1 and 2 thus increasing the SO2 content in the gas to pass 2. This increases the temperature of the gas exiting the second pass, which results in higher temperatures in passes 3 and 4. Comparison of the converter performance prior to and after the changes is made. The benefits of partially bypassing the first pass to increase the SO2 content in the gas to the second pass are shown. Conclusions and scope for further work have been drawn from the comparisons.

Jan 1, 2009

By M. T. Baquera

A comparison of microstructures associated with W single-crystal ([001], [011], [111]) rods prior to deformation (as grown), and after quasi-static compression (at a strain rate of ~1/s) by transmission electron microscopy (TEM) shows several orders of magnitude difference in dislocation density. Dislocation substructures were not significantly different amongst the deformed sample orientations. In contrast, [001] W rods penetrated into steel targets, at impact velocities of ~1.3 km/s, exhibited heavy dislocation densities and dynamic recrystallization as very distinct microstructural regimes accommodating the penetration process. Twinning on {112} also occurred as a precursor to, or remnant of, these microstructures near the projectile head. These results suggest that deformation accommodating the extreme strains and strain rates associated with the penetration of a single-crystal rod into a metal target is not adequately represented by conventional deformation

Jan 1, 2006

By J. C. Yingling

[New stochastic process models are developed to calculate the probability of various fill levels in section feeders as a function of vehicle interarrival times, payloads and feeder-discharge rates. These models may be utilized to establish the minimum feeder-discharge rate necessary to prevent a feeder, with a particular surge storage capacity, from constraining the section's production rate. In addition, it is shown how the output from these models may also be utilized to calculate the probability of various flow rates at junctions in the conveyor haulage network, enabling one to size gathering belts. The model provides a basis for optimizing, (in economic terms) capacity specifications for feeders and conveyor belts in the materials-handling system by considering tradeoffs in the size of the two types of units.]

Jan 1, 1997

By William K. Connor, O&apos

The U.S. Bureau of Mines (USBM), in cooperation with the American Society of Mechanical Engineers (ASME), conducted over 200 hours of melting tests to vitrify residues from five municipal waste combustion facilities. Combined residues (grate residue and f1yash) from three municipal waste combustors, a waste water treatment sludge combustor, and flyash from a refuse-derived-fuel (RDF) boiler, were sequentially melted in a I-metric-ton (mt) water-cooled-wall electric arc furnace. Each of the residues underwent magnetic separation, screen size analysis, and bulk chemical analysis prior to melting. The furnace products were examined by optical and electron microscopy and by X-ray diffraction. Bulk chemical analyses were acquired for the metal, fume, and vitrified furnace products. The material balance for the furnace operation indicates that from 69 to 86 pct of the feed reported to the vitrified furnace product, which had leaching potentials well below the EPA limit for each metal, as determined by the EPA TCLP. The electric arc melting furnace currently is being utilized in a cooperative research project between the USBM and the Idaho National Engineering 'Laboratory (INEL) for melting tests on simulated low-level radioactive wastes,

Jan 1, 1991

By Wern-ping (Nick) Chen

The Florida Department of Transportation District 6 (FDOT D6) began a study in 1987 for a master plan to improve the traffic circulation and congestions between the Port of Miami (POM) and downtown Miami, FL. This study included a tunnel connection between two man-made islands, the Watson and the Dodge islands. Though a finding of no significant impact (FONSI) was completed in 1992, the project remained on hold for about 10 years. In 2002, Florida Turnpike took over this project, re-evaluated its benefits to the lo-cal communities, determined its feasibility (specifically the tunnel options) and established a probable cost. In 2005, the FDOT D6 regained its charge over the project and concluded that a bored tunnel under Biscayne Bay is feasible. Its primary components are: ? Widening of the MacArthur Causeway Bridge, to accommodate truck traffic to the Port of Miami. ? A tunnel connection between Watson Island and Dodge Island, where the POM is located. ? Connections to the POM roadway system, either for the traffic from the city of Miami or for the truck traffic from I-395 to the POM. The project will improve access to and from the POM and provide a dedicated roadway connector linking the POM with the MacArthur Causeway (State Route 41/1) and I-395, specifically for the trucks in and out of the POM without going through downtown Miami. As identified in the project information memorandum (PIM), its primary objectives are to: ? Improve access to the POM, helping to keep it competitive and ensuring its ability to handle projected growth in its cruise and cargo operations. [ ] ? Improve traffic safety in downtown Miami by removing POM traffic, trucks and buses from the congested downtown street network and, in doing so, facilitate ongoing and future development plans in and around downtown Miami.

Jan 1, 2009

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

By Raymond C. Voige

"The use of current electronic technology in the design of new underground mine communications equipment is providing improved and expanded voice communications which can, in turn, contribute to improved productivity and safety. A review of equipment that is now available or under development Includes the following categories:WIRED SYSTEMSI.Pager phones with selective calling, audible and visual alerting and message indicator.2. Mufti-conversation pager phones that use multiwire cable ormultiplexing techniques.WIRELESS SYSTEMSLow-and medium-frequency inductive systems utilizing ""near"" magnetic fields for both vehicular and personal communications.Wired SystemsCommunication systems in underground mines have evolved slowly in many parts of the world. For many years, magnetotype telephones were the only means of communication from one mine level to another and to the surface. These units were located near the shaft and communications to the working areas were limited."

Jan 1, 1981

The coalmining industry in most countries has, at various times, suddenly been confronted with a decrease in demand for coal. Readjustments made to reduce productive capacity to match the reduced demand for coal have often resulted in hardship to mineworkers, loss of capital investment to mineowners and loss of coal reserves. The consequences of the methods of readjustment adopted in the past have contributed to the low esteem in which coalmining has come to be regarded by a large section of the gel).eral public in many countries.Four sections of the coalmining industry, representing different periods of time, different countries, and different methods of industrial organisation have been examined:Great Britain and the U.S.A. during the inter war years, the post war European Coal and Steel Community, and post war Great Britain under the National Coal Board. An assessment has been made of the methods adopted in each case to reduce productive capacity to match a reduced demand for coal. Finally the fundamentals of the problem-as it affects the coalmining industry of any country-are considered, and possible solutions put forward.During the 1950's, surplus productive capacity was a problem in many coalmining countries, including Australia and New Zealand. As a rule no techniques are developed beforehand to solve problems introduced by a sudden decrease in demand for coal. The situation is usually tackled by a series of short term decisions based on expediency, which often in the long run only aggravate the problem.

Jan 1, 1961

By G. G. Barbante

The oxidation behaviour of selenide matte with a substantial Cu content and low Ag differs significantly from that of high-Ag matte. Low-Ag selenide mattes display a large oxygen solubility and the upper boundary of the miscibility gap in the Ag-Cu-Se-O system is depressed to quite low Se contents. As a result, the formation of Ag metal is considerably delayed. The oxidised selenide matte, low in Se and with a relatively high oxygen content, has previously been termed oxymelt. With further oxidation, its composition enters the misciblity gap and crude Ag is formed. The sodium silicate slag captures very little of the SeO2 and the dissolved Ag2O(s) content of the slag is relatively small, with a Raoultian activity coefficient of 0.57. This value was found to be independent of the slag's Cu2O content

Jun 19, 1905

By Y. F. Liang

Fe-6.5wt.%Si alloy has excellent soft magnetic properties compared with conventional silicon steel. It is very brittle at room temperature due to appearance of ordered phases, like B2 and DO3. In this paper, we investigate the effect of ordering on cold workability of this alloy. Methods of rapid quenching and hot rolling were utilized. It is found that rapid quenching and proper heat treatment of the hot rolled sheet could decrease the degree of order due to the very high solidification rate and high cooling rate. The rapid quenched sheet and hot rolled sheet after proper heat treatment could be cold rolled without crack. Microstructure, phase ordering, micro hardness, and cold rolling properties were investigated by Optical Microscope, X-ray Diffraction, Micro Hardness Indenter and Four-high Mill.

Jan 1, 2009

By D Laurence, L Ge

This paper demonstrates use of remotely sensed imagery in promoting sustainable mining. Remote sensing technology can be used during all phases of a mining project û from evaluating the resource, to making extraction more cost-effective, through to monitoring, mine closure and remediation. Use of the new generation of satellite platforms with the capability of acquiring satellite data with higher spectral and spatial resolution have the capability to emerge as essential indicator for sustainable development in the minerals industry. A life cycle approach to satellite imagery is discussed. The use of an imagery of the site prior to mining activity establishes the environmental baseline, guides mitigation measures and eventual help in suggesting remediation. Remote imagery provides the cost-effective means of monitoring reclamation, including the growth of planted vegetation, of the mine site and surrounding area. The latest advancements in satellite remote sensing are highlighted to meet the newer challenges of sustainable mining practices. Some of the worldwide successful remote sensing applications for the measurement and evaluation of the sustainable development impact of mining operations are described. Presently available source of imagery and its comparative advantages and disadvantages are provided as a guide. Finally, the limitations of this tool are indicated.

Jan 1, 2009

By Zenón Quispe

El presente trabajo describe la importancia de la aplicación de técnicas de análisis de cuencas sedimentarias en la exploración de minerales del área de Cajamarca. Para ello, se determinaron los espesores originales de las Formaciones Chimú, Santa- Carhuaz, Farrat e Inca y los porcentajes de disminución de espesor y con los resultados obtenidos, se diseño y analizó el gráfico de curvas corregidas por descompactación y sin corrección por descompactación. Asímismo, se explica la posible formación de fallas no tectónicas debido a la compactación diferencial y las unidades estratígráficas que comprende el estudio.

Sep 9, 2007

The Hyde Macraes Shear Zone (HMSZ) is an extensive low angle semibrittle mineralised structure in the Otago Schist Belt, New Zealand. The shear zone is located on the lower limb of a late metamorphic recumbent fold. Structural observations suggests that the shear zone initiated as a high strain mylonite zone and transgressed the ductile/brittle boundary (D4) later in its development. A surge zone at Round Hill is bounded to the south by a NE-SW striking lateral ramp which displaces the hanging wall shear (HWS) by 50 m. Oblique strike slip displacement during surge zone propagation created space for deposition of the sheeted vein complex or stockwork. Quartz recrystallisation in stockwork veins suggests that the veins were deformed in a ductile manner and implies that surge zone propagation may have occurred during late D3 deformation. A macroantiform was produced during D3/D4 shortening below the HWS. Over tightening of the antiform hinge created SW and NE-dipping ramp thrusts. Continued strike slip displacement along the lateral ramp rotated the antiform and associated ramps into a south plunging drag fold. Post-mineralisation (D5) structures include NE-dipping nonna! faults below the HWS and SW-dipping low angle imbricate thrusts above the HWS. The development of these structures was kinematically compatible with normal movement on the HMSZ and is related to mid Cretaceous break up of Gondwanaland in the SW Pacific.

Jan 1, 1992

By JOHN JANNEY

STABILIZATION of the adjustment of normal consumption to normal production of world commodities is quite different from reducing production until visible surpluses are consumed. The first means restoration and maintenance of prosperity, the second means merely a temporary alleviation of a condition with the prime cause remaining uncorrected. Overproduction of foodstuffs in some sections of the world while millions starve in other sections represents not so much overproduction of foodstuffs as mal-distribution of foodstuffs. The flour mills of Washington and Oregon normally ship quantities of flour to China. Now, the wheat that would make this flour goes East instead of West. Is this overproduction, or is there something wrong that calls for study, analysis and correction? Can the plan used by the ostrich of hiding its head in. the sand get us by this present world tragedy, or must the challenge to solve this problem be met, constructively? Can we not make out of this breakdown in the world's economic system an opportunity? And use it as the stimulus for remedying the basic cause of the trouble and not content ourselves with devising temporary expedients that aim at remedying this or that of the obvious conditions, in themselves not causes at all but rather the evidence of causes, or that are the symptoms of the real trouble.

Jan 1, 1931

By R Zhou, B J. Monaghan, S J Chew, R J. Longbottom, D J. Pinson, H Li, P Zulli, G Zhang, L Lu

Steelmakers are increasingly motivated to use iron ore resources with a wider range of grades and mineral types that were previously considered unsuitable or uneconomical for sintering. In this respect, specific issues, which now require further investigation and understanding, include the sintering of ore types with:- overall higher gangue content- elements that cause problems in the steel manufacturing operations- distinctive sintering performance compared with traditional hematite-rich iron ores. Laboratory-based investigations of the sintering performance and the behaviour of gangue impurities during sintering is an important step towards the successful utilisation of these resources in steelmaking.In terms of laboratory-based sintering investigations, there are two generally accepted experimental scales utilised prior to undertaking industrial-scale trials, which include: bench-scale tablet (compact) testing and pilot-scale pot testing. The former has the advantages of flexibility and more precise control of sintering conditions; but it is difficult to simulate the heterogeneity of a sinter bed. The latter, which is carried out in pots with diameters between 150–500 mm, simulate the commercial sintering process and conditions quite well, but is time-consuming and labour-intensive due to operational complexity. It is therefore desirable to establish a smaller scale pot testing facility that avoids the disadvantages of the normal sintering pot but can provide comparable information.To explore the feasibility of small-scale pot testing, a ‘millipot’ facility was established to examine the sintering performance of iron ores and other non-traditional ferrous materials. The millipot has a diameter of 53 mm and height of 400 mm. The facility has the capability to monitor the sintering temperature at a number of locations (axial, radial) within the sinter bed and to adjust the suction (‘windbox’) pressure. This paper describes the development of the millipot facility and operational procedures, together with initial tests undertaken in order to match its performance with industrial sintering performance.CITATION:Li, H, Zhou, R, Pinson, D J, Zulli, P, Lu, L, Longbottom, R J, Chew, S J, Monaghan, B J and Zhang, G, 2017. A millipot set-up for sintering investigation of iron ores, in Proceedings Iron Ore 2017, pp 85–90 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By Lisa R. Papandrea, David Chen, Walter E. Kaeck

"Construction of the University at Buffalo’s new School of Medicine and Biomedical Sciences (UB-SMBS) required excavation in variable ground to a depth of more than 40 ft adjacent to the NFTA Metro subway and Allen Street Station. Complicating the building design and construction, the new medical facility incorporates the at grade Station entrance building, requiring a combination of temporary and permanent excavation support structures, a complex sequence of ground support installation, and a mix of shallow and deep foundations to accommodate the large floor spans and concentrated column loads introduced by building over and adjacent to the Station entrance. Excavation and foundation construction was challenged by a stratified soil profile with interlayered and sensitive sands, silts and clays and complicated groundwater regime with perched and regional water tables. Efficient construction required ongoing coordination between the design team and contractor, careful field observation, and construction monitoring in several facets of below grade construction. This paper describes the design and construction of excavation support structures and foundations to manage the variable ground, congested site conditions, and complications of building adjacent and above an active subway station. Use of site instrumentation and monitoring data to provide guidance in construction when unanticipated field conditions arise is illustrated. Lessons learned in installation and sequencing of excavation support, groundwater control and foundation construction are also discussed.INTRODUCTIONUniversity at Buffalo President Satish K. Tripathi heralded the new School of Medicine and Biomedical Sciences (UB-SMBS) as a future linchpin of UB’s downtown campus that will revitalize the area and enhance western New York’s emerging bio-sciences corridor. The $375 Million, 628,000 square foot, eight story building with two basements is expected to house 2,000 faculty, student and staff allowing UB to increase class size from 140 to 180 students. It will be constructed above the Niagara Frontier Transportation Authority’s (NFTA) Allen Street Station, creating a direct connection to Buffalo’s light rail system. The 200 ft x 400 ft site is bounded by Main Street, High Street, Washington Street and the Roosevelt Apartments and adjoining parking lot at the west, north, east and south respectively, as shown in Figure 2. Groundbreaking for the new building was in October 2013 with the facility scheduled to open in early 2017."

Jan 1, 2016