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By Alesse V, Belardi G

A new class of collectors, Mercapto-Benzo-Oxazoles (MBO), exerting selective action on copper sulphides in the presence of Pb, Zn and Fe sulphides (galena, sphalerite and pyrite), has been synthesised in co-operation with Enichem's Donegani Insitute. The collectors have a mixed aliphatic-aromatic structure and contain functional groups which form chelates with copper. Some reagents of this class having hydrocarbon chains of various lengths have been laboratory tested on a complex sulphide ore containing chalcopyrite, galena and sphalerite in pyritic gangue. Comparative flotation tests have permitted selection of the best collector for chalcopyrite, namely Methyl-Mercapto- Benzoxazole (MMBO). Systematic flotation tests have been performed with this reagent, varying collector concentration, grain size of the feed, pH and flotation time. The results obtained show that the synthesised collector is much better than potassium-amylxanthate (KAX) as regards selectivity towards Pb and Zn. Moreover, it is possible to work at natural pH (6-7) and the flotation rate is higher. In fact in the rougher stage with 80 g/t of collector at natural pH, a copper grade of 7.14 per cent was obtained with a recovery of 73.87 per cent, while the grade with KAX did not exceed 2.11 per cent for a recovery of 73.54 per cent. The amount of Pb and Zn reporting in the copper concentrate was eight per cent and ten per cent respectively, while with KAX it was no lower than 24.34 per cent and 22.71 per cent in that order. After two minutes flotation a copper grade of 5.2 per cent with 52 per cent recovery could be attained, against a grade of 2.5 per cent and a recovery of 44 per cent in the case of KAX. The efficiency of this new collector has been ascertained on two samples of complex sulphide ores of diverse mineralogical composition.

Jan 1, 1993

By D Burgess

Since the days of mandatory high cost pilot plant testing in 6 ft + 2 ft SAG mills autogenous griding/semi-autogenous grinding (AG/SAG), mill specific energy is now calculated by various empirical formulae and pilot testing carried out in small laboratory mills. Barratt (1989) described a method using Bond Indices than adding a single factor of 1.25 to arrive at the AG/SAG specific energy. In 1991 the Canadians developed the SAGPower Index (SPI), test using 2 kg of material in a 300 mm diameter mill. This test has been further developed by Starkey, Hindstrom and Orser (2006). This test now includes a Bond Ball mill work index test.The Macpherson test is still being offered by some testing facilities. This dry test requires at least 180 kg of material.Morrell (2004) formulated an AG/SAG specific energy generator based on a drop weight index Value (DWi). This DWi value is related to the Ab parameter and the material specific gravity. Morrell reconfigured the BondÆs Third Theory formula to cause extra power requirements to be inputed. This technique incorporates the material specific gravity (SG). The AG/SAG specific energy values produced using this method are susceptible to higher values of crushing and rod mill work indices.This paper offered describes a more simple method to generate AG/SAG specific energies. This programme incorporates Bond work indices, the JKMRC parameter Ab measuring impact breakage and the parameter ta measuring the abrasion rate, then employs a series of efficiency values nominated for each transition size (AG/SAG T80). These efficiency values have been compiled over the years from actual operating plants and documented reports.CITATION:Burgess, D, 2012. A method of calculating autogenous/semi-autogenous grinding mill specific energies using a combination of bond work indices and Julius Kruttschnitt parameters, then applying efficiency factors, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 37-44 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

Solid Energy New Zealand (SENZ) uses a 20+ year period for integrated planning of all its business activities. It has an ongoing program of coal resource assessment to optimise future mines within this 20 year period, using a six step resource and mine planning process. Desktop review and conceptual study at preliminary Levels 1 and 2 are based on general coal resource information. Further coal resource investigations are carried out for the more detailed evaluations in secondary assessment, prefeasibility study, feasibility study and detailed engineering from Levels 3 to 6. At Levels 1 and 2, completing conceptual planning, including preliminary resource evaluation and economic appraisal to the target cost uncertainty level of ¦33 per cent, is challenging in New ZealandÆs highly variable geological and geographical conditions. Where coal deposit geometries are relatively simple, approximate methods for determining pit limits using overburden strip ratios, seam thickness, physical boundaries, and quality cut-offs may be sufficient. Many New Zealand coalfields are however complicated structurally, with multiple seams and extensive folding and faulting. Coal seams are characterised by variable dip, thickness, and quality over relatively short distances. In the North IslandÆs Waikato coalfields, coal is typically overlain by weak sediments and clay rich strata that necessitate very flat cut and fill slope angles. The proximity of these deposits to major infrastructure (including towns, highways and rail lines), significant environmental features such as the Waikato river and lakes, and valuable dairy farmland, add further complexity. Traditional preliminary mine planning techniques applied in these conditions are insufficient. Pit optimisation software, widely used in the metalliferous mining industry since the 1980s, offers the ability to analyse many more specific factors affecting pit limits, mine layouts, and economics, with more rigour and for a much larger number of scenarios, than traditional methods allow. SENZ therefore decided to adapt and use æWhittleÆ pit optimisation software for Level 2 analysis of several Waikato opencast prospects. This paper describes this work.

Jan 1, 2005

Hindered settling devices (teeter bed, up-current) are widely used in the mining industry to classify mineral streams into various size fractions and to separate minerals. In the coal industry these devices are extremely successful in separating coal of low densities from shale and pyrite. In the beach sand and in the iron ore industry, this equipment is used to beneficiate minerals either as stand alone units or lately as classifiers in spiral circuits. The challenge that these applications give to metallurgists is to be able to simulate the equipment by using mathematical models with or without the aid of small bench scale tests. In any green fields and many brownfields projects, limited amounts of samples make pilot plant tests difficult. Although there are mathematical approaches available, the accuracy is of such a nature that it can not be used for design purposes. This refers to the use of StrokeÆs law, NewtonÆs and the so called intermediate law as is widely published. Research done by the author indicates that in most applications none of the above laws apply. Using the original data as published by Perry and Chilton (Chemical Engineering Handbook, pp 5-64, 1973) and re-plotting it indicates that the settling velocity of particles is a function of (particle diameter)n where n varies between 1.2 and 1.6 which is different from that predicted by the intermediate law that suggests that n = 1.18. Another way of describing the relationship between the drag force and the Reynolds number is done by iterating between settling velocity and the Reynolds number. This needs more computer time but the accuracy obtained from this does add value to simulations. A small but simple test is suggested to determine the settling velocity of particles to enable metallurgists to determine variations from the theoretical calculations to determine the influence of viscosity and particle shape.

Jan 1, 2008

Lafayette Mining Limited, a listed Australian company, is developing a polymetallic Project on the island of Rapu Rapu, located to the east of southern Luzon in the Philippines. The Rapu Rapu Project is based on the Ungay deposit, which has proven and probable reserves of 6.0 million tonnes of 2.5 g/t Au, 28 g/t Ag, 1.2 per cent Cu and 2.1 per cent Zn. The Project will produce copper and zinc concentrates from a sulphide flotation plant as well as dore from a CIL gold plant. Average annual metal production over the projected six-year mine life is 9800 tonnes of copper, 14 000 tonnes of zinc, 50 000 ounces of gold and 590 000 ounces of silver. Despite a rich mineral endowment and long mining history, there have not been any significant new mine developments in the Philippines since the early-1990s. The investment climate has been affected by legal challenges to the 1995 mining code, civil unrest in parts of the country, the impeachment of the previous President and community concerns about the industryÆs environmental performance. As a consequence, the Rapu Rapu Project is viewed as a test case û within both the country and the international mining industry û on whether minerals investment in the Philippines is an acceptable business proposition from a risk perspective. Lafayette has faced formidable challenges in managing the development risks of the Project. The major risk areas of the Project for which the company developed strategies include: regulatory, environmental and approvals issues, technical evaluation, project development, social and community issues, land acquisition, and financial and marketing issues. This paper describes the risk management strategies successfully pursued by the company, and which have the Project on track to commence construction in 2003. Dealing with each of the areas in turn, Lafayette sought to develop strategies which either effectively neutralised, minimised or otherwise addressed the key risks most likely to be experienced.

Jan 1, 2003

By R Herbert, M E. Malmstr÷, S U. Salmon

The study focuses on sulfide oxidation processes in unweathered pyrite-rich mine tailings from a soil-covered impoundment in northern Sweden. To simulate the oxygen-limited conditions in water saturated tailings two long-term column experiments were performed. Results are presented for the first 11 months of the experiments at room temperature. The tailings used in the experiments were of two different grain sizes (one coarse grained, in the range 0.02 - 0.6 mm with a grain surface area of 1.86 m2 g-1, and one fine-grained, in the range 0.0015 - 0.06 mm with a grain surface area of 10.00 m2 g-1) and with slightly different mineralogical composition. The S:Fe molar ratio in the leachates (1.0 - 1.5) indicates either that pyrrhotite is the main iron sulfide undergoing oxidation in our experiments, or, alternatively that the S:Fe molar ratio in the leachate is determined by pyrite weathering in conjunction with other processes releasing iron or immobilising sulfate. However, speciation modelling of the leachates indicates that ferrihydrite was close to saturation, suggesting that a ferric oxyhydroxide may have dissolved/ precipitated during the experimental period, thereby affecting the S:Fe molar ratio. Pyrite oxidation rates obtained from the two column experiments during æsteady-stateÆ were 2.25 + 10-13 and 8.45 + 10-14 mol m-2 s-1 in the coarse and fine tailings, respectively. Pyrrhotite oxidation rates, as an alternative, were 2.31 + 10-12 and 1.24 + 10-11 mol m-2 s-1 in the coarse and fine tailings, respectively. Natural microbial activity was confirmed in both the tailings and the leachates; therefore, the obtained oxidation rates are not strictly abiotic. It is thus concluded, based on the experimental results, that tailing heterogeneity will result in zones with different oxidation rates, related to their physical and chemical properties.

Jan 1, 2003

Mr Chairperson, respected leaders of the mining industry, ladies and gentlemen;   Good morning, Kiora, Nihao.   I am very honoured to give a speech to the 2005 New Zealand minerals conference. I would like to take this opportunity to express my sincere thanks to the Ministry of Economic Development to invite me to be part of this important event.   Today, I am going to talk about two themes: a brief introduction of ChinaÆs economic development, including ChinaÆs energy strategy; the good bilateral relations between China and New Zealand, its potential for further development and its relevance to our cooperation in the field of minerals and energy.   It is a well-known story that over the past 27 years, great changes have taken place in China. In 1978 when ChinaÆs reform and opening up just started, its gdp was near to only 150 billion usd dollars. By the year of 2004 it reached to 1.6 trillion usd, an average of yearly growth rate 9.4 per cent.   ChinaÆs great achievements are widely appreciated both in China and abroad. ChinaÆs development has not only improved the living standard of its own people, but also produced a huge market and brought about great opportunities for the world. Since ChinaÆs entry into WTO in 2001, China has imported near to 1.8 trillion usd dollars of goods, averaging a yearly imports of 500 billion usd dollars, creating for other countries and regions more than ten million jobs.   Our prediction is that in the next five years, ChinaÆs imports will be well over three trillion usd dollars. China will continue to serve as one of the leading growth engines for the future world economic development. Now China is on its great strive to achieve the goals of improving living standard for all the Chinese people. We are trying to reach a quadruple gdp of 2000 by the year of 2020, namely to reach gdp four trillion usd, a gdp per capita 3000 usd dollars.

Jan 1, 2005

Structural geological modelling is a process which results in a 3D computer model that represents the essence of the geological and structural understanding of an area and is presented in a way that is directly useable, typically by internal customer groups. BHP Iron Ore operates a number of open cut iron ore mines in the Pilbara Region of Western Australia. The largest mine is the Mt Whaleback Mine located at Newman close to the southern margin of the Pilbara Craton. The structurally complex Mt Whaleback Mine is the largest metalliferous single pit open cut mine in Australia with over 1.6 billion tonnes of original iron ore resource. Additional to the Mt Whaleback Mine, a number of satellite open cut iron ore mines are operated by BHP Iron Ore (BHPIO) in the Newman area. BHPIO also operates the Yarrie mine approximately 400 km north of Newman at the northern edge of the Pilbara Craton Most of the BHPIO mines are located in the Archean- Proterozoic Hamersley Province that overlies the Archean granite-greenstone terrain of the Pilbara Craton. The orebodies are considered to be the result of supergene enrichment of the approximately 2.5 Ga Brockman Iron Formation and the slightly older Marra Mamba Iron Formation. Folding represents the most prevalent and penetrative structural element in the Newman area. Four folding phases have been identified regionally (Fj, F2, F3, F5), while a more local folding deformation (F4) developed mainly in the Mt Whaleback and Orebody 29 mine area. A northeast trending, southeast dipping, 45 km long, high angle, normal fault zone, the Whaleback Fault Zone, cuts through the Mt Whaleback mine resulting in an approximately 1400 in gap in stratigraphy. Additionally, two large, low angle, normal faults, the East Footwall Fault and the Central Fault, are present at the Mt Whaleback Mine. During the formation of supergene orebodies, up to 40 - 45 per cent volume loss occurred resulting in local non-tectonic deformation in the orebodies.

Jan 1, 1997

An investigation was made into the mineralogical characteristics of the upper portions of the 650 and 750 copper lodes. The investigation was based on a comprehensive suite of geological specimens representing all types of mineralization encountered during mining until the end of 1954 and the chief aims of the investigation were to determine (a) the minerals present and their textures and associations, (b) the paragenetic sequence of deposition of minerals in the orebodies, (c) significant changes, if any, which could be found in the orebodies with depth, and (d) the nature and mode of occurrence of nickel in the ore. The general structure of the orebodies is outlined and their mineral composition given. 10 textures exhibited by the ore minerals are described and a paragenetic sequence of events in the formation of the copper orebodies is outlined. No decrease in the complexity of the sulphide mineral textures with depth could be seen and no evidence was found to suggest that the tenor of the ore would decrease with depth although some factors which may eventually limit the extent of the orebodies are noted. The mode of occurrence of minor elements in the orebodies is described. Notes on the occurrence of pyrite, aikinite and berthierite in the orebodies is given and the orebodies are considered to be identified with LiIidgren's mesothermal type of sulphide ore deposit in which considerable replacement of older by younger generations of sulphide minerals occurred.INTRODUCTIONA mineragraphic study was made by Stillwell and Edwards (1945) of a suite of specimens submitted by Mount Isa Mines Limited from the Mount Isa Black Star copper orebodies with a view to determining 1. the nature, extent and association of arsenic, antimonyand bismuth minerals, 2. the mode of occurrence of silver and 3. whether galena and sphalerite occurred in minute forms and below the sizes readily observed in hand specimens.

Jan 1, 1961

By C McIntosh, M Carder, P M. J Durance

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. Disseminated, gold-bearing sulfide minerals hosted in sheared, wall rock metasediments and clay alteration zones comprise one of the dominant styles of Palaeozoic orogenic gold mineralisation within the Reefton Goldfield, and is exemplified by OceanaGold’s Globe Mine. This study begins the exploration and characterisation of the gold-arsenic-antimony mineralisation hosted within the dominant lithologies of the Globe-Progress shear zone. The main gold-bearing sulfides are pyrite, arsenopyrite and stibnite. Pyrite and arsenopyrite are not compositionally uniform across the Globe-Progress shear zone. Pyrite from the mineralised greywacke and argillite has higher As contents than pyrite in the host rock and pug breccia. Furthermore, the mineralised greywacke and argillite pyrite are enriched in As from core to rim. The 3D models based on bulk assays reveal a significant correlation in the distribution of Au, As and Sb. The interpolant for Sb envelops those for Au and As, which in turn are very similar to each other in their vertical and lateral extents across the shear zone. This result is consistent with earlier findings that the occurrence of stibnite represents a separate and likely later phase of mineralisation relative to that represented by the formation of disseminated pyrite and arsenopyrite both of which exert a stronger control on the distribution of As.CITATION:Durance, P M J, Christie, A B, McIntosh, C and Carder, M, 2015. The composition of disseminated, gold-bearing sulfides within the three-dimensional framework of bulk Au, As and Sb in the Globe-Progress orogenic gold deposit, Reefton Goldfield, New Zealand, in Proceedings PACRIM 2015 Congress, pp 327–334 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By Glenn R. J

Treatment processes are outlined for the recovery of rutile and zircon from the heavy mineral-bearing sands on the east coast of Australia. With the exhaustion of the higher grade deposits and the imposition of more rigid specifications for the finished products, strict metallurgical control has become necessary.A description is given of the methods used by The Titanium Alloy Manufacturing Co. Pty. Limited to control the operation of suction dredging, of wet concentration using fans and spirals, and of dry separation using high tension and electromagnetic processes. By applying these methods a plant designed for an output of 15,000 tons of rutile per year has been tuned to produce over 20,000 tons of rutile and a corresponding amount of zircon.Details are given of (a) the method of drilling to determine the extent and grade of the ore bodies, (b) a simple electrically-timed pneumatic automatic sampler, and (c) the methods developed for the physical estimation of quartz, rutile, zircon, ilmenite and "others" in the products of plant operation.The method used for calculating the metallurgical balance and the forms used for the reporting of production results are presented.Examples are given which show the value of this detailed production and metallurgical control of plant operation.INTRODUCTIONThe organization which is now known as "The Titanium Alloy Manufacturing Co. Pty. Limited" (T.A.M.Co.)-a subsidiary of National Lead Company-commenced operating at Yamba, N.S.W., in 1935. A mixed natural concentrate was at first simply dried and bagged and later was upgraded by the removal of silica and the lighter heavy minerals on shaking tables and, after air-drying, was bagged for export. At that time zircon was the most wanted constituent.

Jan 1, 1960

To provide suitable backfill material for the cut and fill mining method being used to extract ore from the C.S.A. mine, flotation tailings are deslimed in single stage cyclones. The sand fraction is stored on the surface in unagitated storage bins before being pumped underground, while the slime portion is thickened and pumped to a residue dam. Design and operating details of the sand preparation and storage sections are given.The initial preparation of a stope for filling, consists of laying percolation and decantation drainage pipes on the sill floor. Preparation for fllling of subsequent lifts consists of rearing up the ventilation pipes at the ends of the stope, preparing the decantation system, and building a barricade or wall. The fill is carried to, and discharged into, the stope through 4 in. diameter pipes and filling of any section is carried out 24 hr/day normally without supervision. The fill is retieulated underground to the 1200 ft level through rubber lined pipe installed in the upcast shaft. Boreholes of 3 in. diameter drilled from the1200 ft level convey fill to the 1800 ft level. The mine drainage system is basically designed to handle the water associated with hydraulic filling. A system of primary and secondary sumps has been installed to handle the percolation and decantation drainage from stapes and to allow settling of fines before the water is fed to the main pump station.A programme of investigation into the properties of the emplaced fill is in progress. Results to date indicate that the fill as presently placed and drained, will not cause any problems in the mining of vertical orebodies by cut and fill methods for lifts in excess of 300 ft.

Jan 1, 1969

A broad zone of intra-plate volcanism occurs for some 3000 km along the E. Australian coastal regions, extending from far northern Queensland southwards to Tasmania, westwards to western Victoria, and into southeastern South Australia. The age range, taken over the whole region, extends from Eocene to Holocene. Wellman & McDougall (1974) recognised the occurrence of three distinct types of volcanic occurrences: (a) Lava field provinces, dominantly basaltic and commonly strongly undersaturated, but of variable size. Large lava fields are especially exemplified by the younger provinces in northern Queensland (e.g. Nulla, McBride), and western Victoria. (b) Central volcano provinces, in which a reasonably well defined volcanic edifice is discernable. Such provinces are built of mildly undersaturated to saturated mafic lavas, but are also characterised by felsic volcanism (and often substantial mafic and felsic intrusive phases). Examples are the Springsure-Minerva Hills province, the Tweed and Focal Peak Shields (southeastern Queensland to northeastern N.S.W.), and the Nandewars, Warrumbungles, and Canobolas volcanic centres (N.S.W.). (c) A single leucitite province in N.S.W. Wellman and McDougall (1974) were able to show that the central volcano provinces exhibit a remarkably regular southward age migration pattern, the calculated migration rate being 66 + 5 mm yr , and these authors interpreted this in terms of the northward passage of the Australian plate across a fixed 'hotspot' within the upper mantle. The leucitite province also fits this migration pattern. The lava field provinces apparently exhibit more erratic regional age distribution patterns, but Sutherland (1981) has interpreted the data in terms of a multiple 'hotspot' model. It is noted, however, that the youngest areas of volcanism (Pleistocene 1. Department of Geology and Mineralogy, University of Queensland, St. Lucia, Brisbane, Queensland

Jan 1, 1987

By A F. Cooper

The northeast-southwest trending ~25 km2 area incorporating Bald Hill is located 18 km northeast of Haast, and 5 - 7 km west of the Alpine Fault in South Westland, New Zealand. The geology consists of Greenland Group greywacke overlain by a Cretaceous-Tertiary sedimentary sequence and fluvio-glacial/marine terrace deposits of Quaternary age. Alluvial gold in Cole Creek, draining west from the summit of Bald Hill, may be derived either from vein mineralisation in basement rocks or from fluvial or marine terraces.   This paper focuses on the potential for in situ gold and base-metal mineralisation in sporadic, siderite-rich quartz veins that cut basement greenschist facies metasediments that have been overprinted by contact metamorphism.   Throughout the area, vein compositions are dominated by quartz and commonly feature zoned plagioclase. Alteration adjacent to veining within the contact aureole is dominated by 1 - 2 mm, coarse grained biotite, with small amounts of sulphide, and is pervaded by abundant siderite veinlets. Outside the aureole, wall rock alteration to veins consists of fine grained chlorite. Trace element XRF analysis has been used to ascertain base metal concentrations within samples of vein and alteration zones collected from throughout the area. Vein and alteration zone mineral assemblages containing <5 per cent sulphide, with low concentrations of As, Cu, Pb and Zn indicate low potential for gold and base-metal mineralisation in the Bald Hill region. Contact metamorphism of Greenland Group basement in the northeast of the region, is likely due to emplacement of a poorly exposed Cr- and Ni- enriched gabbro. The presence of biotite and andalusite in hornfelses indicate contact metamorphism occurred at temperatures >350¦C and at depths <10 km. Widespread vein distribution does not appear to be related to contact metamorphism or gabbro emplacement. Further research is required in order to establish the fluid source from which the veins were precipitated.

Jan 1, 2007

IN carrying out experiments to determine the amount of metal taken away by fume or fine dust the apparatus used requires to be strong and compact, as it is generaIIy necessary to work on a staging fixed at considerable distance above the ground and against a smoke stack or flue. It is essential that the test be carried out at a part of the stack welI away from any bends, to prevent eddies. The method described below has been used for estimating the dust losses from Dwight & Lloyd sintering machines, antimony drossing furnaces, pot sintering trials, etc., and has been founc! satisfaetory. It is welI to bear in mind that the longer the period over which dust coIIection is extended, the more valuable the result is likely to be. The rateof aspiration of the gases through the apparatus is kept as regular as possible by changing the filter thimbles frequently, and the rate of flow should correspond closely with the rate of flow of the gases up the stack.The apparatus required for carrying out a test is as folIows :-{a) Thermometers : two are required, one for taking the temperature of the gas in the stack and one for giving the temperature of the gas in the aspirating drum. If the temperature in the stack is over 400° C., it is advisable to use a pyrometer such as the "Bristol" the couple being standardized before use at about the temperature of the stack.(b) Pilot Tube: The foIIowing sketch (Fig. 1) iIIustrates the principle of the pitot tube. The readings are to be taken in a straight flue, or stack, preferably 20 diam. away from any bend. A, which is open, faces the air current and...

Jan 1, 1922

Although the effects of sea level changes on ore concentration processes are to some extent obvious with certain deposits, e.g. beach placer deposits, they have been largely overlooked with others such as Mississippi Valley type lead-zinc deposits. It is contended that sea level variations may have more profound effects on a wide range of deposits than has previously been appreciated. These deposits include not only placer'and residual deposits but also stratiform copper deposits, Mississippi Valley type deposits, stratiform manganese deposits and Minette type iron deposits. Sea levels in paralic basins profoundly affect the influx of 'detrital sediment, and this has to be suppressed to allow for the accumulation of thick rich deposits of coal evaporites, phosphate or metalliferous sediment. Emergence can be associated with oxidized waters, erosion, and,solution of soluble rocks. Submergence can reverse the Eh trend and can lead to preservation of ores. Both realms of surficial sedimentary environments and subsurface diagenetic environments can be affected by changes in water pressure, gas pressure (pC02), Eh, pH, and temperature as sea levels fluctuate. Even relatively small sea level changes may have profound effects. For example, there is some evidence to suggest that when the level dropped below 100 metres about 10,000 years ago, the Red Sea became isolated by the sill at Bab el Mandeb in the south, and evaporated away to leave a series of shallow lakes. The Red Sea is 1 to 2 km deep. It was at times such as this that the well-known copper-zinc mineralization developed in the Red Sea trough. Changes in sea level also affect the stability field of gas hydrates which can yield large volumes of gas leading to mass movements on the sea floor (Warnke, 1986).

Jan 1, 1987

The reduction of titanium tetrachloride to trichloride can be achieved by employing hydrogen and electric arcs. It is possible to produce melts containing up to 50% TiCk in the eutectic mixture of LiCl/KCl by striking a D.C. arc at the surface in the presence of hydrogen and TiCl. vapour. If the electrode IS made to just penetrate the surface of the salt mixture, a hot zone results from the' high resistance contact with both lower chlorides and sintered titanium may be produced. The sintered metal forms just below the melt surface while the trichloride forms at the gaslIiquid junction.The "hotspot cathode" appears to offer a solution to the problem of producing coherent deposits as the spong'e metal can 'be continuously withdrawn in a similar manner to the "calcium process".INTRODUCTIONConsiderable interest has been shown for some years in the possible development of a cheap electrolytic process for the extraction of titanium metal, since a method using simple materials and cheap electric power would materially reduce the cost of production. Even when cheap starting materials are used, however, there exist several general difficulties in the operation of plant which both limit the speed of production and increase the cost of the product. It happens that most of the techniques so far tried produce a powder as cathodic deposit, and when this is the case the following difficulties arise:1. The whole contents of the bath must be treated with solvent in order to extract the 'metal powder which may itself tend to oxidise, and thus become contaminated.2. Fine metal powders, which often contain residual entrained salts, are less easy to consolidate by arcmelting than metal sponge.

Jan 1, 1956

By Shuguang L, Jing S

Computer controlled truck dispatching systems is a newly-developed technical system in surface mines with shovel-truck technology. The real time dispatching criteria, as the core of optimal truck dispatching software, are analysed and a new criterion, complex dispatching criterion, is put forward. Dispatching criteria previously proposed include: 1. `Earliest Loading' (EL) - to assign a truck to the shovel at which the truck can be loaded earliest. 2. `Max Truck' (MT) - to assign a truck to the shovel at which the truck will have the shortest waiting time. 3. `Max Shovel' (MS) - to assign a truck to the shovel which has been waiting for the longest time. 4. `Minimum Saturation Degree' (MSD) - to assign a truck to the shovel at the branch where the truck flow saturation degree is minimum. 5. `Minimum Saturation Degree with Truck Cycle time consideration' (MSDTC) - as the MSD principle, with the truck travel cycle also considered. 6. `Fixed Dispatching' (FIX) - to assign trucks to fixed shovels. A system simulation model has been set up for truck dispatching system analysis. A few surface coal mines have been selected for case studies. Equipment waiting times and shift production of the system are obtained as the main outputs of the model. Simulation results show that each dispatching criterion has its own applicable range, no one can absolutely dominate the others. For example, when under-trucked, EL and MT criterion can obtain higher production than the MS criterion; when over-trucked, it is vice versa; while for MSD criteria, better results can be obtained no matter how the truck numbers fluctuate. From the view point of shovel output balance, large fluctuations occur for EL and MT criteria, while a good balance can be obtained for other criteria. In the light of dynamic change of mining system conditions, a single dispatching criterion is not necessarily reasonable. A complex dispatching criterion has been put forward to seek the complex optimum effect. Taking the advantage of each dispatching criteria, the dispatching result of a complex dispatching criterion dominates over individual dispatching criterion and a comprehensive optimum effect can be reached.

Jan 1, 1995

By T Mizuta, T Nakano, D Ishiyama

The Tamagawa Hot Spring, from which Ra-Pb-Sr-bearing barite precipitates, is a representative hot spring in a volcanic gas-bearing hydrothermal system associated with Quaternary andesitic to dacitic magmatic activity beneath the Yakeyama Volcano. Thermal water in the Tamagawa Hot Spring is divided into three types: Cl-SO4-type (Ohbuki hot spring: pH 1.2); SO4-type (pH 1.8 to 2.9); and neutral-type (pH 6.1). The concentrations of dissolved components in the Ohbuki Cl-SO4-type thermal water are about ten times higher than in the SO4-type thermal water. The 87Sr/86Sr isotopic signatures of the Ohbuki Cl-SO4-type thermal waters (0.703992 ¦ 0.000004 to 0.704032 ¦ 0.000006) are different from those of SO4-type thermal waters (0.704245 ¦ 0.000003) formed by the interaction of andesitic volcanic rocks (0.704065 ¦ 0.000007 to 0.704093 ¦ 0.000009) and groundwater derived from river water (0.704314 ¦ 0.000012 to 0.704519 ¦ 0.000013) in a shallower part of the hot spring area. The possible origins of Sr in the Ohbuki Cl-SO4-type thermal water and in the SO4-type thermal water are different. The Sr isotopic ratios (0.704130 ¦ 0.000012 to 0.707556 ¦ 0.000014) of Aniai Formation andPreYakeyama Lake deposits occurring below the hot spring area are distinctly higher than those of the Cl-SO4-type thermal water. However, it is expected that a solidifying andesitic or dacitic magma which has similar Sr isotopic ratios of the Ohbuki Cl-SO4-type thermal water, occur in the deep portion of the Tamagawa Hot Spring. The Cl-SO4-type thermal waters having low Sr isotopic ratios do not acquire their Sr isotopic signatures by interaction with strata below the hot spring area, but they are likely to reflect water interaction with a solidifying magma with low Sr isotopic ratios. Components including rare metals in Cl-SO4 type thermal water could be transported from a deeper part. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By A Kuras

Segmental tunnel linings are becoming more common in Australia. One current project employing a segmental lining is the City West Cable Tunnel (CWCT) in Sydney. The project has been commissioned by Energy Australia and is currently being constructed by Thiess Pty Ltd. The project includes 1.6 km of tunnel boring machine (TBM) driven, segmentally lined tunnel. The majority of the CWCT will be excavated through Hawkesbury Sandstone. The tunnel is required to carry a 132 kV electrical circuit under SydneyÆs central business district (CBD), between Haymarket and Energy AustraliaÆs City North Substation on Sussex Street. The segmental lining has been designed as a 3.2 m internal diameter, 200 mm thick universal ring with six trapezoidal segments. The design and detailing of this segmental lining presents some noteworthy challenges, including exposure to saline groundwater, and the exclusive use of steel fibres for flexural and tensile concrete reinforcement. This paper describes some of the key elements of the segmental lining design. These include:the case for choosing segmental linings over other forms of tunnel construction;the major design checks required of a segmental lining including ground loading, hydrostatic loading, joint bearing, joint rotation, ram loading and the early strength lifting case;the benefits of using steel fibres over conventional steel reinforcement;the design approach used for steel fibre reinforced concrete;the application of 3D computer modelling in the design;the provision for components including connector dowels and gaskets;the design for passive fire resistance; andthe design for durability of steel fibre reinforced concrete in a saline environment. Segmental lining design requires the application of specialist design approaches. Input is required by the construction team, as the methods of demoulding, handling, transportation and installation impact on the lining design. As the segmental lining is functioning as immediate ground support and also a permanent lining, high standards of manufacture and construction quality control are required to ensure that the 100-year design life is met. The requirement for a watertight tunnel means that detailing and installation of the EPDM gaskets is of importance.

Jan 1, 2008