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High pressure (-1.2 GPa) Early Cretaceous granulite facies orthogneisses in Fiordland, New Zealand are in tectonic contact with a cover sequence comprising mid-Palaeozoic amphibolite facies metasediments, subordinate metavolcanic rocks and syntectonic granitic orthogneisses. This cover sequence and the underlying granulites constitute upper and lower crustal plates of a mid-Cretaceous metamorphic core complex whose emplacement was linked to continental rifting and the Late Mesozoic breakup of the Pacific margin of Gondwana. Exhumation of the lower plate granulites occurred in two stages. The first stage was associated with extreme attenuationand tectonic denudation of the cover sequence accompanying emplacement of the core complex, leading to rapid uplift of the granulites but without generating the large volumes of Fiordland-derived sedimentary detritus normally expected if uplift and erosion were the only factors involved in unroofing the granulites. Final uplift and exposure of the granulites at the surface occurred mainly during the last 10 Ma in response to transpression across the mid-Tertiary Alpine Fault and/or the obduction of Fiordland continental crust over oceanic crust of the Tasman Sea.

Jan 1, 1990

The purpose of the Lower Lea Valley Cable Tunnel project is to relocate the overhead power lines circuits, which currently cross the proposed site for the 2012 London Olympics in East London. This was the first contract to be awarded as an Olympic project and is on the critical path for the proposed Olympic Park as the construction of the Olympic village, stadium and other venues cannot begin until the tunnels are complete, the cables installed and the overhead power lines removed. The tunnelling works for the scheme include two parallel tunnels between Hackney and West Ham. Each tunnel is approximately 6 km in length. One tunnel is 4.15 m ID and connects the National Grid substations. The other is 2.82 m ID and connects the EDF Energy substations. The tunnels were constructed through mixed ground using four earth pressure balance tunnel boring machines. These were driven simultaneously from two drive shafts within a single site. The 12 km of main tunnels were constructed within a year from start to finish, with completion in June 2007. The shafts range between 6 m and 15 m ID. These were constructed using a combination of caisson sinking and underpinning techniques. Dewatering was adopted to suit the groundwater conditions.Other works include the design and construction of the head house buildings, cable and ventilation culverts, mechanical and electrical (M&E) installations and all associated works. In addition to the above, a further 1 km of tunnel and two shafts were added to the project scope connecting the EDF Energy tunnel to the substation at Bow. These additional works provided further challenges to the project to ensure that these works were constructed within the program constraints for the 2012 London Olympics. This involved refurbishing one of the tunnel boring machines from the main EDF Energy tunnel drives and relaunching the machine to construct the Bow tunnel. The Bow tunnel was constructed within two and a half months, with the tunnel boring machine breaking through in August, ahead of schedule. The main challenge presented by this project is the program constraints. This project outlines the requirement for team work between the client, stakeholders, contractor and designer in order to provide program certainty. A close working relationship between the contractor and the designer is required to provide value engineered, time-saving solutions to mitigate the risks associated with the design and construction program.

Jan 1, 2008

By T Gibbons, M Korte, C Brent, K Runge

The Barrick Osborne concentrator has gone through a number of upgrades since commissioning and steadily increased production from the original 119 t/h design capacity to 265 t/h milling throughput in 2008. This was achieved incrementally over several years, by maximising operating efficiencies, in order to minimise capital expenditure, and take advantages of economies of scale; but more importantly it was reached with no measurable loss of recovery. Osborne currently processes a blend of under- ground with open pit material from the nearby Trekelano deposit. Following primary/secondary crushing, the material is processed through a rod/ball mill grinding circuit ahead of rougher/scavenger flotation that produces a copper concentrate.Osborne was seeking a further increase in plant throughput of the order of 15 per cent, but at more sustainable levels of secondary crusher plant utilisation. In early 2008, Osborne contracted Metso Minerals Process Technology Asia-Pacific and South America (MMPT) to review the entire process from run-of-mine feed to final copper concentrate. This review would be done concurrently, with surveys of both the crushing/ grinding and flotation circuits being performed at the same time. The outcome would be a steady-state model of the complete flow sheet allowing the crushing/grinding model to interact with the flotation circuit model such that overall process optimisation was possible. Two key outcomes for the operation are exploration of the operating limits of the currently installed plant, and projection of the logical next stage of potential capital plant expansions. This paper covers Part B or the flotation component of the project. A separate paper discussing Part A or crushing and grinding is also being presented at this conference. Surveys of the Osborne flotation circuit were performed along with a comprehensive review of the cell characteristics including measurements of the gas and froth phases of individual flotation cells. These data resulted in a size-by-size floatability component model of the complete circuit. This circuit model was then used to perform steady-state simulat- ions to evaluate options to improve both overall circuit and individual cell performance. The grinding circuit model discussed in a separate paper or Part A of this project was then used interactively with the flotation circuit model to recommend the best operating regime to maximise overall efficiency. For example, the balance between increased crushing and grinding costs versus higher copper recovery and final concentrate grade. Due to changes in market conditions in the fourth quarter of 2008, the focus was shifted to prioritising operational changes rather than capital expansion modifications, in order to improve circuit performance.

Jan 1, 2009

Through the stress synthesis of many examples of macrostructure in the middle of China, it can be concluded that in the middle of Chinesetectonics there are two compression-torsion-forces, one of which ( from NW to SE ) came from the northwest side of Aerjinshan abyssal and giant fault("F1A", see Fig.7,8,9 ); the other (from S to N ) came from the south side of the north piedmontal fault of Kunlunshan-the south piedmontal fault of Qinlingshan ("F2K-F2Q", see Fig-7,829 ).Owing to the two compression torsion forces a new special type of structure named rotation-apart structure occurred from Chaidamu basin to Hebai, Henan, Anhui plain,from Caledonian movement, Hercynian movement,Yenshan movement to Himalayan movement, step by step In the north of Qilianshan during the late Caledonian movement: during the Hercynian movement it extended into a vast area including the Chaidamu basin and Eerduosi basin; during the Yenshan movement it spread over the whole area of Helanshan,Eerduosi basin and Hebai , Henan, Anhui plain. In the period of Himalayan movement all these structures revived .The rotation-apart structure controlled the distribution of all mineral deposits and also were the mineralizing structures.The relation between these rotation-apart structure and earthquakes is very close.

Jan 1, 1990

By Smith DM Jr

Silver deposits, in which silver forms at least fifty percent of the value of the ore, are abundant and large on the east side of the Pacific and are absent in the western Pacific. To determine if this uneven distribution is related to features of consuming plate tectonic boundaries which dominate the metallogeny of the Pacific Rim, the variation of Ag/Au in porphyry copper deposits was used to estimate the relative silver content of magma generated in subduction zones. Porphyry copper provinces with high Ag/Au occur in regions of the eastern Pacific where silver deposits are abundant, suggesting that the distribution of silver deposits is controlled by the relative abun- dance of silver in subducted ocean crust. Ocean crust being subducted in the eastern Pacific is mostly less than 50 million years old in contrast to most ocean crust in the western Pacific which is much older. Enrich- ment of silver in young ocean crust at spread- ing centers may reflect metallogenetic evolution over geologic time. Silver may be transported to the surface in volcanic rocks, and deposits are common where felsic varieties are abundant. The high ,solubility of silver in natural waters provides a natural storage mechanism for silver weath- ered from these rocks and ultimately circulated in near-surface hydrothermal systems where many silver deposits form. The regional distribution of silver deposits is not influenced by discoverability, vertical metal zoning, or regional tectonic style. The effect of igneous differentiation is unclear.

Jan 1, 1987

By R-H Yoon

Increasing the upper particle size limit of flotation would allow operators to increase mill throughput, save operating costs, simplify flow sheets, and increase rate of return. However, coarse particle flotation is difficult for various reasons, of which bubble-particle detachment has been identified as the major limiting factor. In the present work, the process of bubble-particle detachment has been studied by directly measuring the forces required to detach air bubbles from hydrophobic solids. The measurements were conducted using a hanging balance apparatus. The measured forces were converted to detachment energies that can be compared with the work of adhesion, which in turn is a function of hydrophobicity, surface tension and contact area. The results were converted to detachment energies using the Young-Laplace equation for capillarity. In the present work, the solid surfaces were hydrophobised by coating them with octadecyltrichlorosilane and cetyltrimethylammonium bromide. The results show that bubble-particle detachment occurs in two steps. In the first step, air bubbles are deformed, while the three-phase contact (TPC) line is pinned, until contact angle reaches advancing angle. In the second step, the TPC line moves along the surface until solid/air interface is replaced by solid-liquid interface. In general, the energies of detachment measured in the second step are in good agreement with calculated work of adhesion. Thus, the energy required during the first step effectively represents an energy barrier for bubble-particle detachment. It has been found that the energy barrier varies with surface roughness and surface tension. The results of the present investigation suggest, therefore, that coarse particle flotation can be improved by control of particle hydrophobicity, surface roughness, and surface tension.

Jan 1, 2005

The Engineering Chemistry Division of the Government Chemical Laboratories of WA initiated an ongoing investigation into the possible utilisation of diatomites of this State. The work has shown that local diatomites can be beneficiated by hydro or pneumatic cyc- lone separator circuitry and that the better quality head materials can be upgraded by straight and flux calcination and associated processing to the equivalent of premium grade imported products. Western Australian diatomites vary con- siderably in quality, and the degree to which they can be upgraded and the yield of useful product are influenced by the proportion of impurities and the size, type, and degree of fragmentation of contained diatoms. Conseq- uently careful assessment of ore deposits will be necessary in order to relate ore reserves to planned production. The viability of commercial production from Western Australian resources would hinge on the establishment of markets - largely ex- port - capable of supporting a production level of the order of 30,000 tonnes per annum.

Jan 1, 1979

By Sen G

An amount of explosives, whether it be cylindrical, spherical, etc in configuration, with a hollow cavity in one face or end is known as a hollow or shaped charge. When this charge is initiated, a focussing of explosive energy will occur within this cavity. This focussing, or concentration of detonation products creates an intense localised force greater than just the simple detonation of a conventional explosive, (without a hollow cavity). If this hollow cavity explosive is directed against a target material this concentrated force is capable of creating a deeper penetration than the same amount of explosive without the hollow cavity. If a metallic liner material is used in the hollow cavity, upon detonation of the explosive this liner will form into a high velocity penetrating jet. Depending on the explosive type and the liner material's configuration the jet tip can travel up to 10 km/s. Linear shaped charges were developed using the abovementioned shaped charge concept but instead of being formed about an axis, they are elongated and constructed along the principal axis. Therefore instead of creating a narrow circular penetration jet, it forms a thicker planar cutting jet ideal for linear cutting purposes. Using Linear Shaped Charges (LSC) for pre-splitting is expected to result in more accurate directional fracture propagation, while minimising lateral micro fractures in the surrounding rock mass which is required to remain undamaged.

Jan 1, 1995

By Fernando N, Guang LX

Brown coal in Victoria in spite of its substantial reserves is not utilized greatly because of its high moisture content(-65% w/w). Transportation and handling costs of raw brown coal, on an available energy basis are so expensive that 93% of production is burnt for electricity generation on or adjacent to the coal deposit in Victoria. With direct firing of moist brown coal in power stations, approximately 20% of the gross calorific value of the fuse is used to evaporate the water contained in the coal. This energy is lost as vapour with the flue gas which is vented to the atmosphere. Also there is a 25% increase in flue gas volume and the size and cost of most of the units through which it passes must be appropriately larger. Since there are large quantities of water present the flame temperature is significantly reduced. For zero excess air and no air pre-heating the theoretical flame temperatures are: 609'o wow moisture 1450¦C 40% ª ª ª 1790¦C ZOO ª ª ª 1990¦C As a result of this there is a reduction in radiant heat transfer leading to a requirement for a two fold increase in radiant tube area. A boiler of much greater size and cost is thus required to house the additional tubes. Figure 1 illustrates the relative sizes of a boiler fired with 60% moisture brown coal with a boiler or similar output fed with a British bituminous coal, 14% moisture.

Jan 1, 1989

EQUIPMENT TO BE DISCUSSED It is the intention of this paper to discuss the transporting of large skid mounted equipment and track machines around open cut mines. By large I mean 100 to 350 tonne capacity being trans- ported on minesite lowloaders and the capability of moving loads of 300 to 1200 tonne by other means. It is also possible to move larger loads. The main factor in transporting large loads is eco- nomics and is a balance between the cost of the transporter and the increased production from the equipment being moved. For example it could be possible to shift a 7000 tonne dragline faster than their own means of propulsion, being the "walking feet" method. However for the cost of $10 to $12,000,000.00 or more you can afford to walk the dragline and suffer the production loss. Let us concentrate on the economically realistic. BOSICH FBT MINESITE LOWLOADERS 100 TO 350 TONNE CAPACITY. Why initially consider having such a transporter? Our experience has shown that initial enquiries evolve from mines requiring to move large drills, 50 to 200 tonne weight and large hydraulic excavators or backhoes which are track mounted. The reason for shifting them is to move equipment from a mining face to enable blasting, to remove to the central workshop for repairs, overhauls and routine maintenance, to transport equip- ment from one mine face to another, and for drills, to move from one drilling pattern to the next. The cost in terms of time lost and extra wear on tracked equip- ment easily justifies the cost of the transporter. The tracks on large drills and shovels are not intended for long distance walk- ing. These tracks are designed to move the machines to position for drill holes, or moving around the mine face. Long distance travel, ie generally 1 km or more, results in overheating of track rollers, track drive components and accelerated wear on tracks.

Jan 1, 1989

By Wright S, Rogers L. J, Precious T. H

Brown coal and its char were investigated as substitutes for petroleum coke in the manufacture of anodes for Hall-Heroult cells. The char, which had been densified by several techniques, was made into compacts with various binders and the anodic consumption determined during electrolysis. The results were an improvement on previous work, but the anodes still fell short of acceptability for use in aluminium smelters because of intractable microporosity. Some options for future development have been discounted.

Jan 1, 1986

By Koppe JC, Strieder AJ

The Rivera Crystalline Island (RCI) is an erosional window of the intracontinental Parana Basin that outcrops in the Rivera Department, north of Uruguay. RCI is made up mainly by Precambrian granites, metasediments and granite-gneisses. This island is crosscut by a dextral transcurrent shear zone system, the Rivera Shear System (RSS). The bulk strain ellipsoid was defined by previous work and has allowed the evaluation of shear dynamics. The geometry of the shear system is made up of two shear directions: E-W (P-shear), which turn right to NW-SE direction (R-shear), leading to the development of extensional bends. The shear zone system was developed in brittle-ductile to brittle regimes, under temperature conditions compatible with greenschist facies metamorphism. The shear zones are marked by an intensive fracture cleavage development. Mylonites develop only in narrow, discontinuous higher strain zones. Internally, the shear zones are dominated by intrusive rocks, mainly granites, dacites and diorites. Hydrothermal alteration has been developed in several areas.The economic significance of RCI is given by several small gold deposits, which have been exploited since 1869. One major new gold mine is under development, the San Gregorio Gold Mine. This gold deposit is locally controlled by a dilatant site where R-shear turns right to P-shear. Mine lithologies were deeply altered by hydrothermal fluids in the dilatant structure. This work presents the lineament-structural analysis carried out to identify similar structural patterns in all RCI sites favourable to host other gold deposits. The exploration program also considered remote sensing, geology, geophysical and geochemical survey.

Jan 1, 1997

By Watsford RMS, Wickham P

In October 1980 the two existing flotation circuits were combined into a single new circuit. This circuit used modern 11.3 m3 flotation cells which replaced 1.4 m3 units. Sometime after this change, a significant deterioration in metallurgical performance occurred. This paper describes the work done to discover the causes of deterioration in performance and actions taken. The program implemented to prevent a future occurrence is also presented. The work included analysis of routine plant data, analysis of surveys to obtain element and mineral flows on both a sized and unsized basis, some quantitative mineralogy, and analysis of some external factors.

Jan 1, 1978

Techniques and results achieved during the excavation of the Melbourne Underground Rail Loop (HURL) are summarised and discussed in the context of the various restraints present in a typical urban construction project. Mechanical methods (as distinct from those utilising blasting)accounted for the bulk of the excavation. Ground support was critical in this particular geological excavation setting, but is not discussed in detail except insofar as it constitutes a restraint to excavation progress.

Jan 1, 1978

An account of milling "methods and costs at Mount Isa Mines Limited up to the year 1938 has been published. The present paper outlines the methods since adopted in the milling of lead-zinc ores and presents a description of the equipment now being provided for the milling of copper ore.The programme approved for the mining, milling and smelting of both lead-zinc and copper ores involves the milling 9f 50,000 tons of lead-:-zinc ore and 35,000 tons of copper ore per month.The crushed ores will be delivered to the surface from alternate levels through No. 2 Ore shaft and conveyed to their respective crude ore bins at the crushing plant. The ores will be crushed and milled in separate circuits in common buildings and the tailings will be stored on a common tailings dump. The water services to the two circuits will be separate.LEAD ZINC PLANTCrushing PlantThe crushing plant described in the previous paper was located adjacent to the Urquhart shaft. The crushing plant had grown considerably over the years by the addition of a 4ft. BY-mons shorthead crusher and a set of Traylor 72 in. x 20 in. crushing rolls and, whilst operating satisfactorily, was difficult to maintain and cramped in many places. As a satisfactory layout for the new copper crushing plant could not be made in the vicinity of the, existing plant, it was decided to construct a new plant on the western side of theconcentrator building and provide identical equipment in...

Jan 1, 1953

By I J. Holland

Located in North West Queensland, XstrataÆs Mount Isa Copper Operations (MICO) is one of the largest underground mines in Australia with annual production exceeding six million tonnes of ore with average copper grades of three per cent. As at 30 June 2006, the Ore Reserve inventory totalled 87 Mt, with annual diamond drilling planned at >40 000 m in order to convert existing resources and test and define exploration targets. The role of the geology department within MICO is to collect, interpret and communicate relevant geological information to ensure the optimal extraction of ore. Routine underground inspections across multiple ore sources are undertaken and the information derived is then distributed to a range of professionals, operational personnel and management. The information is a æreal-timeÆ geological view for the stakeholders. Ongoing data collection and interpretation has developed a strong geological input to all mine planning processes within MICO. This has created strong synergies between mine planning professionals and a throughput benefit has been seen all the way to the concentrator. The MICO geological framework also provides avenues for a geological focus away from short-term production requirements, and as a result significant orebody scale observations and patterns have been realised that have led to an increase in the accuracy of geological and resource models. This has provided practical benefits for short-term scheduling and production, whilst enabling the realisation of long-term benefits that have a strong potential to increase the volume and value of the MICO resource. This paper will discuss the various mine geology contributions at MICO and illustrate some examples where mine geological input from graduate level has added significant value to the MICO business.

Jan 1, 2007

Major discrepancies between mine estimates and estimates from plant metallurgical balances are a common problem in many gold and base metals mines around the world. Many existing practices are based on practical protocols that often fall short

Jan 1, 1998

By P A. Gow, J L. Walshe, G J. Masterman

The Eocene-Oligocene porphyry belt of northern Chile contains the worldÆs largest accumulation of porphyry-related copper metal. Conflicting models exist regarding the relative importance of strike-slip and reverse faulting during the emplacement of the porphyry and epithermal systems, based on regional studies and also from work at the Chuquicamata deposit. In contrast, at the Collahuasi district, high sulfidation state copper-silver mineralisation was superimposed into the core of the Rosario copper-molybdenum porphyry deposits along normal faults during gravitational collapse of the Domeyko Cordillera. Exhumation of the porphyry environment occurred rapidly during this event, allowing near-surface epithermal mineralisation (<200 m paleodepth) to be juxtaposed into the potassic altered core of the porphyry deposit (estimated depth of formation: 1300 m) in the space of approximately one million years. Mass wasting after major episodes of tectonic uplift provides an effective method of hypogene upgrading of porphyry ores by high sulfidation mineralisation.

Jan 1, 2005

Economic and technical reasons forced the mining industry all over the world to increase the unit size of mineral processing equipment. in large flotation cells, this development leads to problems in areas of air dispersion and keeping solids in suspension. Outokumpu, an operating mining company, designed and developed a mixing mechanism for large flotation cells at its own concentrators and also studied problems related to tank design. Ideal conditions for flotation can only be achieved if the flow pattern created by the mixing mechanism fits well into the tank configuration and the risk of short circuiting is minimized. In large deep flotation cells, four different zones can be found which improve the behaviour of large cells when compared to small cells. Selectivity is increased and in some cases final concentrate grades can be produced from the rougher cell. The largest units have also been used as final cleaners in some installations. When modernizing old plants by installing fewer larger flotation cells, immediate and substantial savings in power consumption are achieved. Additional power savings are made in pumping costs because of simpler circuit design and decreased circulating loads

Jan 1, 1978

By M D. Rosengren, G Gregor, M F. Young

Over the last 15 years the silver/lead/zinc ore treated at Mount Isa became increasingly complex and lower grade. Metal recoveries dropped dramatically, causing a serious decline in profitability. The ætraditionalÆ response of increasing tonnage to reduce unit cost was unsuccessful, since the additional tonnage was even lower quality ore. A major technical and capital program in the 1990s restored metallurgical performance, but business return was still too low and ore quality continued to decline. In 1996 a new, holistic approach integrated the steps of geology, mining, concentrating, smelting, and refining. Previous assumptions about æfixedÆ and æmarginalÆ costs in mining and processing were shown to be wrong. Detailed analysis showed that some ore sources were reducing profit. This led to a fundamental redesign and downsizing of both Mount Isa and Hilton mines. The result was dramatic increases in head grades, metallurgical performance and plant stability without any capital expenditure. The business is now smaller, but more profitable.

Jan 1, 1998