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By Ulrich Schwarz-Schampera

Submarine hydrothermal vents and associated mineralization on the Tonga arc have been identified in the summit calderas of two shallow-water volcanoes. The highest temperature vents (up to 270°C) occur at water depths between 430 and 540 meters below sea level (mbsl) near the summit of one volcano at 24°S (volcano 19). Clusters of large barite, anhydrite, and sulfide chimneys on the summit cone are vigorously discharging clear hydrothermal fluids with temperatures on the seawater boiling curve. There is abundant evidence of phase separation and associated gold and base metal precipitates. Pyrite, marcasite, wurtzite-sphalerite, tennantite, and chalcopyrite line the interiors of the highest temperature vents. Acid-sulfate alteration of basalts and basaltic andesites is evidenced by intense silicification and the presence of abundant alunite. One volcano at 21°S (volcano 1) has a chain of explosion craters on the flank of a neovolcanic scoria cone and associated massive pyrite, barite and native sulfur deposits at a water depth of 210 mbsl. Intergrowths of pyrite and enargite are associated with intensely argillic altered basaltic andesites. The reported alteration and Au-enriched mineralization styles of these vent fields are similar to other shallow water hydrothermal systems at island arc volcanoes and contribute to the diversity of seafloor hydrothermal activity in the western Pacific region.

Jan 1, 2010

By U. Schwarz-Schampera, P. Stoffers

The main characteristics of the 2545 km Tonga-Kermadec subduction system are the subduction of the Pacific Plate and its sedimentary cover in the Tonga-Kermadec trench and the extension and rifting of the lithosphere behind the active island arc in the Lau basin - Havre Trough back-arc systems. The subduction of the Louisville Seamount chain at 25.6°S affects the tectonic and volcanic system and separates the island arc into the Tonga arc and the Kermadec arc, respectively. To the west, a Miocene island arc is represented by the Lau-Colville ridge. The crustal extension between the Lau-Colville and the Tonga-Kermadec ridge started at about 6 Ma, and induced their separation and the onset of the southward rifting since about 5 Ma. Characteristics of the Tonga-Kermadec arc system include (i) the fourthfold decrease of the subduction rate from 24 cm/a in northern Tonga to 6 cm/a in the southern Kermadec trench, mainly north of 23.5°S; (ii) the development from fast spreading in the Lau basin (16 cm/a) to slow rifting (2 cm/a) in the southern Havre Trough with the transition from spreading to rifting at 23.5°S; (iii) variations in the composition and the volume of the subducting sediments and rocks (detritus from the Samoan hotspot at the northern Tonga arc; the aseismic Louisville ridge at the southern Tonga arc; increasing terrigenous sediments from New Zealand at the southern Kermadec arc); (iv) a number of active volcanic centers younger than 1 Ma and characterized by significant shallow submarine hydrothermal systems.

Aug 24, 2006

By W. White

The manuscript of this paper was not available for publication when the Proceedings went to press. Should the author elect, he may distribute copies at the time of the Symposium.

Jan 1, 1986

By Peter M. Herzig

In 1994 and 1998 the German research vessel R/V Sonne undertook detailed mapping and sampling of the largely uncharted offshore areas of the Tabar-Lihir-Tanga-Feni island chain in the New Ireland Basin of Papua New Guinea. The New Ireland Basin occupies a fore-arc position with respect to the formerly active Manus-Kilinailau arc-trench system and hosts a series of Pliocene to Recent alkaline volcanoes which are built on rifted Miocene sedimentary basement. Several of the volcanoes possess high-level porphyry stocks and active geothermal systems, including gold-depositing hot springs and the giant (40 million ounces) Ladolam gold deposit on the island of Lihir. On the southern flank of Lihir island, a group of three volcanic cones were discovered at water depths from 1.000-1.500 m. The volcanoes are located in a narrow zone of recent seismic activity and elevated heat flow (up to 100 mW/m2). The recovered volcanic rocks consist of fresh alkali-olivine basalts, clinopyroxene-rich basalts (ankaramites), porphyritic phlogopite basalts, and trachybasalts. Unusual gold-rich hydrothermal precipitates were recovered from the summit of the 600 m high Conical Seamount located only about 10 km south of Lihir Island. 1200 kg of sampled material systematically collected with a TV-guided grab from the top plateau (150 x 200 m, 1.050 m water depth) are intensely mineralized with pyrite, marcasite, minor sphalerite, chalcopyrite, galena, tennantite/tetrahedrite, and orpiment/realgar together with traces of anglesite, cerrusite, and amorphous silica in stockwork-like veins. Bulk samples of the vein mineralization consist mainly of clays, silica, and disseminated sulfides, and have an unusual high gold content ranging from 1.2-44.0 ppm Au. In some of these samples, grains of native gold (about 1 micron in diameter) were identified by SEM in pyrite and sphalerite. The gold-rich material also contains high concentrations of silver (up to 1000 ppm) and typical epithermal elements such as As (2.6 wt.%), Sb (0.2 wt.%), and Hg (34 ppm). Similar to epithermal deposits on land, which usually have only low base metal contents, the samples from Conical Seamount contain only minor amounts of Zn (max. 4.5 wt.%), Cu (2.0 wt.%), and Pb (2.0 wt.%). Many of the samples recovered from Conical Seamount are virtually identical to the gold ore at Lihir.

Jan 1, 1998

The Shamrock Gold Mine has been brought from exploration to production within three years. Mining of the openpit is scheduled for June 1990 with commissioning in April of the 180 000 TPA carbon-in-pulp mill on old tailings and rock dumps. The development of a small openpit containing 344 000 tonnes at 3.6 g/t Au in a complex sulphide ore has required extensive metallurgical testwork to optimise recovery, and ensure profitability. The project has been undertaken in a changing economic climate, with increasing restrictive legislation. The decision to mine was further complicated by the escalating cost of installing a heap leach operation in South East Queensland. Decreasing costs of consumables, in particular sodium cyanide, and the opportunity to purchase a suitable transportable mill at a reasonable price made the project robustly viable as a CIP operation.

Jan 1, 1990

The Chinese city of Shanghai is one of the fastest growing in the world. To keep up with the growth, two tunnels, three-lanes each, are being built beneath the Yangtze River to connect Shanghai with the Changxing River Island. To complete such a large project, Herrenknecht Tunneling Systems was brought in to construct the largest tunnel boring machine (TBM) in the world. The first Herrenknecht S-317 Mixshield has a diameter of 15.43 m (50.62 ft). It was built to construct one of the two 7.2-km (4.5-mile) tunnels. The tunnels are part of the Changjiang Under River Tunnel Project and will be at depths of up to 65 m (213 ft) beneath the Yangtze River in Shanghai-Pudong. These two tunnels are to be opened to traffic in April 2010, in time for Shanghai to host the World Expo. More than 20 million people live in the Shanghai area. The area itself has been growing at an extremely rapid pace for more than a decade and is in need of more space. The search extended beyond the natural limits of the Yangtze River Delta. As part of its incredible growth, 500 new vehicles are registered every day. The new tunnels will connect the Changxing River Island, with a population of approximately 600,000 people to the road traffic network. A bridge construction will also provide a traffic link between Changxing Island and the large island of Chongming.

Jan 1, 2007

By Edgardo Fogli, Mario Lampiano, Antonio Nicola

The project is located in the northern region of the People’s Republic of China and was awarded to Impregilo, as sponsor of the Wan Long Joint Venture, in September1997. The project consists of four tunnels for a total length of 88,700 m, with an excavation diameter of about 4.9 m. The lining is made of honeycomb pre-cast segments, connected by PVC dowels and the joints are sealed with elastomeric gaskets. The geology is mainly Limestone, Dolomite and Sandstone. Karst cavities are abundant and are often in-filled with plastic red clay. This has adversely affected the TBM’s progress. Four double shield telescopic TBMs were mobilized to cope with the very tight construction schedule and, at the end of November 2000, more than 80% of the tunnel has been bored. The article analyses the TBMs’ productions in the various geological conditions and the results of different technical solutions adopted at the project.

Jan 1, 2001

By Megan Becker, Aubrey Mainza, Indigo Research Laboratories, Jenny Wiese, Gaynor Yorath, Lucy Little

Particle shape characterisation has an important role to play in mineral processing, to clarify effects of shape on rheology, equipment wear rates, comminution, classification, sizing and flotation. However in industry, shape characterisation is not routine, and the most commonly used shape descriptor in the field (circularity/ angularity/ sphericity) is not invariant. This study aims to investigate shape measurements for a fine particulate ore sample measured with different analytical devices. Two Automated Scanning Electron Microscopy devices with Energy Dispersive X-ray Spectrometry (FEI QEMSCAN® and Zeiss Mineralogic®), and a camera based image-sizer using dynamic image analysis (Retsch CAMSIZER® XT) were compared. Each device was used to analyse the shape characteristics of specific particles in both a coarse sample (–212/+150 µm) and a fine sample (-53 µm) of UG2 platinum ore. Circularity and Roundness frequency distributions obtained from the three devices were then compared. For selected individual particles, circularity showed higher variability than roundness, and the sample circularity distributions obtained by the three devices were completely different. It is clear that circularity data from different studies relying on different devices should not be compared on an absolute scale. The shape parameter roundness was found to be a more robust descriptor than circularity, and it can give a stronger indication of a particulate sample’s shape characteristics on an absolute scale. However, there were still significant differences in the roundness measurements obtained by the CAMSIZER XT and the two Auto-SEM devices, which was attributed to the dissimilar mechanisms of image capture.

Jan 1, 2016

By Thomas P. Meloy

As the importance of particle shape in mineral processing is increasingly recognized as an major variable in predicting the behavior of both individual particles and particle systems, whether it be in dense media, froth flotation, comminution or the flow of particles, new method of shape characterization are being developed, particularly for use on image analyzers. These shape characterization methods may be broadly classified into the analytical, empirical and physical formation methods. Discussed are approaches and the strengths and weakness of each of these methods. Moreover old and new shape measuring techniques are reviewed, particularly the new image analysis methods techniques such as Fourier, Haar, Fractal, Walsh and Delta as well as a variety of other techniques such as tabling, the Cascadograph, settling and L/D ratios. Also discussed are the problems of doing shape research, current progress and the future of the field.

Jan 1, 1990

By David Cole, Paul Cooper, Dale Preece, Jerome Stofleth

The Explosive Destruction System (EDS) has been designed at Sandia National Laboratories for the disposal of chemical munitions (phosgene, mustard gas, sarin etc.), many dating back to World War I. EDS is a portable system that is trailer mounted and consists of a vessel into which a chemical munition can be loaded and opened for neutralization with linear and conical shaped charges. Gases are contained within the sealed chamber. The linear shaped charges split the munition in two and the conical shaped charge (CSC) is aimed at the explosive burster, in each munition, which is detonated by the resulting shaped charge jet, Toxic chemicals remaining in the vessel following detonation are neutralized and disposed of. This paper documents the development of a new CSC needed to reliably detonate explosive bursters in an expanding array of chemical munitions that are beyond what the EDS device was originally designed to eutralize. Design of this new CSC was controlled by the need to deliver energy above the detonation threshold into the explosive after penetrating the outer steel casing, fluid, the burster casing and finally the explosive. Design considerations were driven by jet conditions at the steel/explosive interface inside the burster. Parameters to consider in CSC design include: 1) diameter, 2) liner thickness, 3) liner position in body, 4) explosive weight, and 5) liner shape or interior (apex) angle. The effects of these parameters on final CSC performance are examined in detail. CSC’s that meet the design specifications have been manufactured and tested. The performance of these charges are compared with the original design requirements.

Jan 1, 2002

By Daniel Castelo, Ben Potter

This paper will discuss the most efficient and effective way to use shape charges when considering standoff distances and the amount of an explosive to be used. For each shape charge test that was performed, a one inch diameter copper liner of 90o was used. Different standoffs for each shape charge were tested to see which one would penetrate the deepest into rolled homogenous armor steel (RHC 44). It was determined that a standoff of three cone diameters provides the deepest penetration. In addition to testing for optimal standoff distances, the effects of overfilling as well as under filling a shape charge with explosive was tested against a shape charge with the bare minimum amount of explosive for correct detonation. These “fill” tests were all performed at a standoff of three cone diameters. Overfilling has little to no effect towards penetrating deeper into a target while under filling a shape charge has an effect of shorter penetration. C-4 explosive was the main explosive for all shape charges.

Jan 1, 2011

By Nikaido M, Kanda Y

A rotary type separator has been developed which separates particles on the basis of their shape. This separator was applied to a particle size range of about 50 - 120 ¦m, and to our present knowledge may be the smallest size range ever to be separated. A theory of the separation is given based on the difference of an adhesive force of the particles: the adhesive force between spherical particles and plate is more powerful than that of irregular shaped particles for the same particle size. These facts have been ascertained by the measurement of an adhesive force by a centrifugal method. US and Japanese patents have been obtained on this separator, which consists of a borosilicate glass cylinder of 150 mm outside diameter, 120 mm in width, and an AC electromagnet. The samples used in this study were mixtures of spherical glass particles and non-spherical shaped glass particles. The results are summarised as follows. In the case of mixtures of spherical particles and irregular shaped particles in the weight ratio of 1:1, the spherical content of the spherical product became 70 per cent - 75 per cent, and in the case of 3:1, the content became 87 per cent - 90 per cent, as the result of one separating operation. However, for a mixture of somewhat rounded particles and irregular shaped particles of weight ratio 1:1, the rounded content varied between 58 per cent - 73 per cent. The feed rate of the particles mixtures was about 0.3 g/min. Newton's Efficiency was 20 per cent - 60 per cent. The separator may find application in shape separation of ceramic powder, metal powder or industrial diamond powder.

Jan 1, 1993

By K. Fuenkajorn, J. J. K. Daeme

Ring tension tests have been conducted on 229 mm (9 in) diameter disks of Grande basaltic andesite and Pomona basalt with various center hole sizes in order to study the relationship between ring tensile strength and relative hole radius (hole radius/disk radius). The tensile strength, [ ] decreases as the relative hole radius, [ ] increases. A power equation, [ ] where C and R represent the coefficients of strength and shape, respectively, adequately represents the ring tensile strength as a function of relative hole radius over the range investigated. This equation can be used to distinguish the effect of the hole size from the strength results, to predict the tensile strength of a ring sample containing arbitrary hole sizes, and to approximate the critical relative hole radius of the material tested.

Jan 1, 1986

By Alana Pereira Ramos, Walman Benicio de Castro

Amorphization and martensitic transformation (Ms) characteristics of Ti–Ni-Cu alloy ribbons prepared by melt spinning were investigated by means of differential scanning calorimetry and X-ray diffraction. In these experiments particular attention has been paid to change the wheel linear velocity from 21 to 63 m/s. Then the cooling rates of ribbons were controlled. The effect of this cooling rate and alloy composition on martensitic transformation behavior is discussed.

Jan 1, 2015

By Erwin Flender, Preben N. Hansen, Peter R. Sahm

"Until now FDM-Techniques have been widely used for Modeling Solidification Processes in Castings. Often a rigid, regular type of enmeshment (cubes, , --) have been used. This has the advantage of low CPU-costs, but the disadvantage of a zig-zag presentation of the interface between the casting and the mold. The last point is the reason why FEM-Techniques, giving the possibility of a true presentation of the shape in the enmeshment, are increasingly used. The disadvantage is the high CPU-costs. In this paper, a technique is presented, which uses the FDM-Mesh with the zig-zag presentation of shape and ADI-Algorithms to calculate temperatures and gradients. The new idea is that the calculated parameters are not presented related to the mesh in which they are calculated, but displayed using the true shape of the casting. Such an advantage of both low CPU-costs and shape correct presentation of the calculated results are achieved. IntroductionThe main reason for using a regular type of enmeshment is that it gives the possibility, via ADI-Algorithms, of obtaining a very fast FDM-Technique. The technique presented by P.R. Sahm and P. N. Hansen (1984), and also used by E. Flender (1985), is numerically so stable that average time steps, at least 200 times larger than the limit given by the explicit FDM-Technique, can be applied. To obtain reasonably good results, average time steps in the range of 20 to 50 times the explicit limit seems to be applicable. It should be pointed out,however, that FDM-Techniques can be used on arbitrary nets, the disadvantages being the same as for the FEM-Techniques. This has, among others, been discussed by P.R. Sahm and P.N. Hansen (1984)."

Jan 1, 1986

By Jing Zhan

The fibrous precursor can be obtained by coordination precipitation process, using oxalate, cobalt chloride and ammonia. The composition and morphology of fibrous precursor were characterized by XRD, IR, DTA/TGA and SEM analysis. The results show that XRD pattern and composition of the precursor with fibrous morphology precipitated at pH=9.0 were different from that of ß-CoC2O4?2H2O precipitated at pH=1.0. The mechanism on the thermal decomposition of fibrous precursor was addressed. The influences of various conditions in pyrolysis, including the temperature, time, atmosphere, and the morphology of the precursor, on the morphology, average size and specific surface area of the Co powders were investigated in detailed. At last, the final product, fibrous cobalt powders with diameter about 0.3~0.5µm in size and 40~60 in aspect ratio, were produced by thermal decomposition at 400~500? in the weak reducing atmosphere. The structure of pores in cobalt powders was capillary tube with open ports and the majority was mesoporous.

Jan 1, 2009

By Dale S. Preece, Vanessa S. Berg

Shaped charges are being utilized in defense applications against a wider variety of targets including concrete, rock, and soil. This work was motivated by a heightened interest in characterizing the effect of shaped charge attack on brittle, non-homogenous materials, in particular, concrete damage and penetration predictions resulting from a TOW-2a conical shaped charge (CSC). This paper presents a multi-stage approach for accurately predicting the high explosive detonation and subsequent jet formation due to the collapse of shaped charge liner, the changes in jet length and diameter as a function of standoff distance, and the jet-target impact dynamics. The first part of the analysis approach employs the commercial 3-D Eulerian-Lagrangian hydro-code AUTODYN to predict the shaped charge jet formation. 2-D finite difference Eulerian subgrids represent the explosive and casings components, while thin components like the liner are modeled with Shell subgrids. The Pugh, Eichelberger & Rostoker (PER) jetting theory option is invoked to obtain the jet and slug masses and associated velocities. The jetting data is post processed where the jet velocity gradient and jet mass is used to solve for the new jet length and diameter gradient at a desired standoff. The final computation involves a 2-D fully Lagrangian model in which the jet and velocity gradient is represented by a string of Lagrangian segments and the concrete target is defined as Lagrangian with the newly developed RHT (Riedel, Hiermaier, Thoma) constitutive model. This model has a third invariant dependency that accounts for failure mechanisms in brittle materials.

Jan 1, 2004

By Vladimir L. Konyukh

Robotics is topical for mining owing to deterioration of miner's safety as a depth of winning, limited functions of traditional mechanization and automation, rise of miner's labor cost. Mining robot is an autonomous mining machine with a free programmable control that provides a multifunctional use of working head. After analysis of world publications the database “Technological applications of robotics in mining" has been built. In most cases robots are suggested for imitation of miner's motions. The following shapes of robotics had been classified for mining: technological robot as a flexible controlled mining machine, remote manipulator, mine rescue robot. The problems of both non-repeated environment recognition and telepresence without direct visibility must be solved. The more a robots integration is the less investments and the more efficiency are. Computer simulation of robotics-based mining is founded on a base of 6 robots functional models, Petri nets and library of 30 robotized technologies. There are some examples of mine robotization in the paper.

Jan 1, 1996

By Paulo Couceiro, Manuel Lopez Cano

"The Panama Canal is one of the most important engineering projects of the modern era and plays astrategic role in the global economy and international maritime trade since its inauguration in 1914. Now, a little more than one century later, the final phase of its expansion program, the largest infrastructure works undertaken since its inauguration, has concluded. This expansion program has created a new lane of traffic along the Canal with the construction of a new set of locks – one on the Pacific side and another one on the Atlantic side -, increasing the Canal’s capacity and its impact on the world’s economy even more."

Jan 1, 2017

The topic for my address is Sharemarket Floats - Issues for Expert Valuers. I've decided to focus on three areas where current practice in the preparation of prospectus valuation reports for resource companies might be improved. My central theme is that the valuer for a float should augment the usual assessments of the value of the company or its assets, with some input on the way the share market might value the company's shares when they are listed. I will then look at the valuer's role in relation to vendor consideration, last I will look at his role in providing investors with some input on the risk dimensions of the new company.

Jan 1, 1989