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By D Lozada, A Salazar

Geometallurgy is a tool that, for more than a century, has been present in the implicit operations of mineral beneficiation. There’s a need to understand the characteristics of the material to be processed. This has led metallurgists to ask geologists what type of rock and mineralogy is entering the Beneficiation Plant and vice versa. The geologist needs to understand the beneficiation process in order to be able to carry out the production programming. The paradigm is whether geometallurgy can be applied to small-scale mining or if it is only aimed at large companies that invest millions of dollars to conduct studies. With this work, we provide an example of how geometallurgy can help improve the processes of a small mining company located in Ecuador (South America). We performed characterizations of geological and mineralogical and metallurgical tests in universities and the National Research Institute of Geological Metallurgical Mining. The origin of the theme is based on the fact that gold has been detected in the final tailings. The flotation concentrates meet the standards in terms of the content of economically profitable metals, but this isn’t the case with regards to the percentage of arsenic, which has hindered sales. The hypothesis is: conducting technical and scientific research will optimize the metallurgical process for the recovery of gold and concentrates. The referential framework is the mining geology of the Bella Rica District, current status of the Beneficiation Plant. In the theoretical framework there are parameters of the veins, comminution operations, gravimetric concentration, flotation, and cyanidation. The methodological framework contemplates the characterization of the gold ore, the chemical, mineralogical, textural, metallurgical analysis and the interpretation of the results. Thus, the design of a geometallurgy model of the deposit, with its main characteristics, is a conclusion that serves as a basis for the proposal of the optimization of the metallurgical process.CITATION:Lozada, D and Salazar, A, 2018. Geometallurgy applied to small-scale mining: a case study, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 153–162 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By S Barrow, D Kent

Controlling the access of equipment, and people, has become more critical over the last few years for improving productivity and to meet safety responsibilities imposed by legislated obligations to have safety management systems. Hence Mine Site Technologies (MST) has spent the last three years completing the development of the tagging system to meet the mining industryÆs requirements, particularly streamlining access control. The basic tagging system tracks active Tags carried by personnel, or attached to vehicles and equipment, within underground zones. These Tags are detected (read) by Beacons placed strategically throughout the mine. As a Tag, or Tags, go past a Beacon they are read and the information transmitted back to the main database PC. This allows the current whereabouts of personnel and equipment to be known, as well as the history of their movements. The objectives of implementing the TRACKER Tagging System at Oaky No 1 Coal Mine were to: maintain a count of personnel inbye a particular point, and can alarm when a pre-set number is reached (eg the limit imposed by availability of SCSRÆs, etc); maintain a count of vehicles (and vehicle type) inbye a point, and can alarm if when a pre-set number is reached (eg when rated diesel units exceeds the limit for the ventilation present in that zone); manage the vehicle fleet, by keeping track of various vehicles underground better control and dispatch management of the equipment is achieved; keep track of equipment, knowing the location of equipment (such as forks, baskets, pumps, fans, etc) where last used or stored will minimise the risk of losing gear and assist in keeping inventory to a minimum; and locate personnel in emergency situations, by placing read Beacons throughout the mine the location of all personnel can be known in real time so that in the event of an emergency, their withdrawal can be monitored.

Jan 1, 2005

By A Minchinton

With blasting, all far-field phenomena including, but not limited to, stress wave propagation, fracture, vibration and muck pile formation are intrinsically and irrevocably dependent upon near-field phenomena or mechanisms that we describe using physics-based mathematics typically transcribed into computer codes. The energetics involved in such near- to far-field transitions are not fundamentally relevant as they are simply progenitors of these processes.The notion of explosive energy as a descriptor for explosive or blasting performance is a case in point. These energies, which are generally used in blasting tables, are almost exclusively based on ideal detonation theory alone and do not include the influence of the rock, charge diameter, blasthole length and the late-time dynamic expansion that can be predicted using codes based on non-ideal detonation theory.With decoupled charges in presplits for example, the pressure drop between the charge and the blasthole wall can be simply described to first order using the energy relationship associated with adiabatic expansion. However, a more realistic mechanistic solution involves interacting fluids and turbulence leading to dynamic processes such as the channel effect.CITATION:Minchinton, A, 2015. On the influence of fundamental detonics on blasting practice, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 41–54 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By T Gill, A Faragher, B Scott, V Kakebeeke

In 2000, after six year intensive exploration for high-grade haematite deposits, Rio Tinto included the channel iron deposits (CID) as a specific iron ore target in the Hamersley Province iron ore exploration program. The exploration model was simple and based on the then current understanding of CID genesis. Fundamental to the model was an interpretation that CID deposits after their final accumulation stage could be entirely concealed in their channels. Inversion to mesas and therefore exposure of the CID profile would only occur in areas where the modern drainages follow the ancient and have significantly incised their current bedrock. The model took encouragement from observations at Bungaroo Creek, where large CID accumulations occur in a deep valley incised in the Wittenoom Formation concealed below recent valley fills derived from the surrounding BIFs. Also, in the headwaters of the Yandicoogina system CID occurs below a more recent cover of calcrete and clay. After a number of failed or partially successful attempts, exploratory drilling in 2002 in the Caliwingina valley in the northern Hamersley Range identified significant CID mineralisation. Subsequent drilling programs from 2003 onwards revealed the presence of a large CID system, which stretches from the middle reaches of the Caliwingina Creek to deep under the sediments of the Fortescue Valley, a channel length of more than 30 km. Although the drilling is still somewhat sparse, the geological resource estimation suggests that Caliwingina is presently the third biggest CID system of the Pilbara (after Yandicoogina and Bungaroo Creek) and is of comparable size to the premining Robe River system (1.6 Bt), with comparable Fe-grades to the Yandicoogina global resource grade (57.7 per cent Fe). Large detrital and canga deposits overlie the Caliwingina CID, or interfinger with it, and although the economics of these are presently unfavorable, could ultimately present a low-grade iron resource of slightly smaller size to the CID mineralisation at Caliwingina Creek. Together with the recently discovered Serenity and Solomon deposits, as well as Cabbage Gum Bore and other smaller occurrences, the Caliwingina Creek deposit is part of a major new CID district in the central Hamersley Ranges, approximately halfway between Yandicoogina and Robe River. Although exploration in this new district is still underway, the preliminary indications are that this area will provide a total CID resource well over 3 Bt, and is on a par with the major known CID systems in the Hamersley Province.

Jan 1, 2009

By R K. A Taylor

The growth in production of beneficiated ilmenite products has been one of the most significant trends in the titanium feedstock industry over the past 30 years. In this period, the production of titanium slag and synthetic rutile has grown five-fold to the point where these products represented 56 per cent of total feedstock production in 2000. Additional production capacity is being proposed as the core component of new feedstock supply projects presently under consideration. A high proportion of these products is based on technologies for which the inherent quality of the is an essential factor. Location specific factors also play a large part in determining the cost of production. As the demand for such products grows, and the availability of favourably located sources of ilmenite of suitable quality declines, it can be expected that existing beneficiation technologies will become increasingly constrained. Existing beneficiation technologies, and those which have been developed, but are not yet commercially applied, are reviewed. Future issues which are likely to impact on the cost effectiveness of these technologies, or the quality of final products, are identified. These factors suggest directions for development of ilmenite beneficiation technologies to achieve economic production of the quality of feedstocks which will be demanded by the TiO2 pigment industry in the future.

Jan 1, 2001

By S J. Chen, N Jiang, Y S. Ding, F X. Li, D W. Yin, F Wang

This study assessed the deformation failure characteristics of rock-coal composites with different height ratios. Uniaxial compression tests were conducted using an acoustic emission monitoring system and XTDIC three-dimensional full-field strain measurement system. The results showed that with the increase in rock-coal height ratios, the uniaxial compressive strength of composite samples increased from 5.26 MPa to 14.61 MPa. The evolution of the deformation localisation zone of the composite samples is closely related to the initiation and propagation of the primary cracks in the coal samples. At the moment when the main fracture of the coal samples occurs, there is a large drop after the peak of the stress-strain curve of the composite samples, and the height of the rock samples increased to varying degrees, which indicated that the failure of the coal samples induced the rebound deformation of the rock samples. With the increase in rock-coal height ratios, the rebound deformation amount of the rock samples decreased from 0.042 mm to 0.008 mm, and the rebound deformation rate decreased from 0.210 per cent to 0.010 per cent. Meanwhile, the rock samples’ rebound deformation releases part of the elastic energy to act on the coal sample, further contributing to the destruction of the coal samples. Compared with single composite coal samples, the coal samples of the composite samples have much more failures. In addition, with the increase in rock-coal height ratio, the input energy density, elastic energy density, post-peak release energy density, and residual elastic energy density of the composite samples increased, the dissipation energy density decreased, and the percentage of pre-peak elastic energy density increased from 98.56 per cent to 99.86 per cent. These results revealed the deformation failure characteristics of rock-coal composite with different height ratios and provided a theoretical reference for understanding the underground dynamic rock failures.

Nov 29, 2022

In practice a sampling solution is a compromise of many requirements: the sample should be representative; the sampling system should also be reliable, less than 95 per cent availability restricts the use of the assayed sample for process control purposes; no sample is the worst sample, and investment costs and installation space/layout are frequently a restriction. For instance, online X-ray analysers for process control introduce a delimitation error by the nature of X-ray physics. Thus only in special cases a relative accuracy better than three per cent relative, as one standard deviation, is achieved. A sampling system for process control needs not to be, as representative, for so many sample properties, as one for composite laboratory analysis samples. Sampling system maintenance is also an important issue. There are many sampling systems in the industry which have been difficult to maintain and are in disuse for lack of resources or incentives to keep them running. Pierre Gy developed the most generally accepted sampling theory. One of the main principles is that all particles in a one-dimensional process stream should have equal chances of being included into the sample. A correctly designed and operated transversing cutter comes close to this goal but has limitations in temporal representativity. For slurries an acceptable solution in many cases is to use a fixed vertical cutter(s) in a position where the slurry is well-mixed by turbulence and other means. For online analysis, reliability problems are mostly related to faulty design or installation of the piping system to the analyser. Properties of material processed, process flow sheet and piping details before and after the sampler have to be taken into account when deciding on which sampling arrangement is appropriate. Guidelines and some solutions to these issues are presented in this paper.

Mar 1, 2010

By W D. Rech, K W. Keskimaki

As an integral part of the conversion from rail haulage to conveyor haulage at Henderson, over six kilometres of drifting and several large complex openings were mined. The deepest of these areas was nearly two kilometres beneath the surface, bringing all of the challenges of rock stress and heat that come with mining at these depths. Though many mines operate at these depths, the development of the infrastructure necessary to support a 36 000 tonne per day caving operation brought some unique challenges to the development mining activity. The issues handled include: finding experienced staff for a æfast trackÆ development program; rock bursts and ground conditions; inflow of 50 degree centigrade water; acceleration of the project completion; large diameter raise boring and difficult muck handling.

Jan 1, 2000

By K Faure

At Sams Creek a peralkaline granite porphyry dyke hosts gold-bearing sulfide-quartz-siderite veins. The granite dyke intrudes Ordovician-Silurian metapelite and quartzite, and has thin lamprophyre dykes along its contacts. The mineralised veins and the granite and lamprophyre dykes have been deformed during several phases of folding, the youngest of which is Early Cretaceous. The granite has been hydrothermally altered, with early magnetite-siderite¦biotite alteration overprinted by sulfide and quartz-siderite veins and quartz-perthite-albitesiderite-pyrite-rutile¦sericite alteration assemblages. The sulfide veins are composed of arsenopyrite + pyrite ¦ gold ¦ galena ¦ sphalerite ¦ chalcopyrite ¦ pyrrhotite ¦ graphite, with minor quartz and siderite. The gold contains significant silver (up to 30.8 wt per cent) and ranges in fineness from 692 to 844. Immiscible liquid-rich fluid inclusions, in quartz protected from recrystallisation by enclosing arsenopyrite, contain carbonic liquid that homogenised at temperatures of 320 - 355¦C. The Sams Creek gold deposit is distinguished from the orogenic gold deposit type by its stockwork veining, magnetite-siderite¦biotite alteration, high sulfide content, ore mineralogy and the absence of mineralisation in the metapelite country rocks. Features of the Sams Creek gold deposit do not fit neatly into existing classifications of granite-related gold-bearing deposits. The peralkaline composition of the Sams Creek granite and the absence of molybdenite and paucity of chalcopyrite, are major points of difference with gold-rich porphyry copper deposits. The presence of a lowsulf idation-state ore mineral assemblage, carbonate alteration and carbonic fluid inclusions at Sams Creek are typical of many of the reduced granitic intrusion-related type of gold deposit. However, notable differences are: the reduced type granites are metaluminous and calc-alkaline; and Sams Creek only has high As in contrast to elevated Bi, W, As, Mo, Te, and Sb in the reduced type. The Sams Creek deposit also shows affinities with gold deposits associated with alkaline magmatism, and it appears to be a new variant of this type as an As-Au deposit associated with a peralkaline granite and lamprophyre.

Jan 1, 2004

By A Grigg, L Hackett

Alcoa operates two bauxite mines at Huntly and Willowdale, located within the jarrah forest south-east of Perth in Western Australia. Ore reserves are shallow but extensive, and mining pits averaging around 20 ha in size are distributed across a mining region in a mosaic pattern, linked to a centrally-located crusher by a radiating network of haulroads. A mining or crusher region is defined partly in terms of economic haul distances, and new regions are opened once the current regions’ reserves have been mined. Since commencing in 1973, the Huntly mine has constructed and progressively closed three previous mining regions and is presently in a transition from the fourth and current region of McCoy to the new region of Myara. At present rates of production, approximately 450 ha is cleared, mined and rehabilitated each year.The value of topsoil in returning a diverse mix of native jarrah forest plant species and supplying nutrients, organic matter and soil biota to rehabilitated areas has long been recognised. Managing the topsoil resource is therefore a critical element in the success of rehabilitation outcomes, but the distribution and dynamic nature of mining operations pose significant planning and logistical challenges. The regionalised approach to mining at Huntly also presents a range of issues for what are, in effect, soil management plans for episodic mine closure. The nature of mining and rehabilitation operations are described, together with the planning processes that Alcoa follows to quantify, track and report on soil movement. A case study of the Huntly mine demonstrates that an integrated operational and life-of-mine planning process is essential for successful and cost-effective mine rehabilitation.CITATION:Hackett, L and Grigg, A, 2014. Topsoil management for long-term mine operation and closure – a case study from Alcoa's bauxite mining operations in south-west Australia, in Proceedings Life-of-Mine 2014 , pp 609–614 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 16, 2014

By Hoskings R

Conceptual studies of the run of mine stockpiling and reclaiming requirements com- menced in 1975. Final selection of equipment was made in 1978 and the equipment was commissioned in June, 1979. Equipment selection was made after extensive investigation and visits to existing facilities throughout the world. The equipment selected is described and com- pared with the alternatives. Foundations were designed to minimise clean up effort and to ensure stability of equipment under design wind loading without storm bays. Program- mable logic control enables the stacking and reclaiming facility to provide a blended feed to the coal preparation plant.

Jan 1, 1980

By D Howe, J Conn, J G. McLellan, K Gates

The Red October Gold Mine, owned by Saracen Gold Mines Pty Ltd, is located approximately 80 km south of Laverton, Western Australia. It is considered to be of a similar nature to many of the Archaean granite-greenstone deposits in the Laverton Tectonic Zone, and presents as an intriguing and relatively young deposit in terms of developed structural and genetic models. Regional deformation events have been proposed for the area, and are relatively well accepted. The most important of these deformation events in the region were the D4b (WNW–ESE sinistral transpression) and D5 (ENE–WSW dextral transpression) which have been attributed to the main Au mineralising phases. At the local scale there appears to have been a rotation of the regional stress field to provide the optimum orientation of maximum principal stress for sinistral movement on the main shear zone.Fully coupled 3D finite element analysis (FEA) was used to simulate the geomechanical response of the system based on structural observations. The geomechanical modelling resulted in highlighting anomalous patterns of stress and strain and subsequent fluid flow as a result of the two main deformation events. The D4 simulation provided a good correlation with the known distribution of subsidiary structures on the main shear zone, and furthermore provided several geomechanical targets that suggested locations of additional subsidiary structures. The D5 simulation provided a great insight into the response of the main shear zone and known subsidiary structures also highlighting additional targets indicating potential for further mineralisation. These targets have since been followed up with a 732 m deep surface reverse circulation (RC) drill hole, resulting in the discovery of two high-grade shoots, with follow up testing currently planned for mid-2014.CITATION:McLellan, J G, Conn, J, Howe, D and Gates, K, 2014. Structural controls and strain partitioning in the Red October Gold Mine, Western Australia, in Proceedings Ninth International Mining Geology Conference 2014 , pp 315–322 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 18, 2014

By M J. Nimmo

extremely powerful tools for building predictive and generative models. ML can be used for building highly accurate regression and classification models. But without careful data science and statistical analysis, a regression or classification model could be highly biased and completely wrong – and we may not even realise. An example rock density estimation task will be used to illustrate the potential gains and possible pitfalls in using ML and AI in Mineral Resource estimation. What could possibly go wrong? Nothing! For most simple regression or classification problems, very little. For density estimation, using the global mean may be all that is possible, but the resource classification would need to reflect the uncertainty in global estimation of tonnage. Everything! From data collection and measurement, from selecting ML and AI techniques and designing the analysis workflow to our own cognitive bias. The things that could go wrong are vast and may include but not limited to asking the wrong question, not asking questions, data bias, measurement errors, insufficient data coverage, not collecting the right variables, not collecting enough observations, collecting clustered samples, unbalanced data, filtering out data without reason (outliers), clipping data (outliers), relying on automatic feature selection, including irrelevant variables, excluding relevant variables, geological interpretation, changing context, blindly following best practice, splitting small data sets, subsetting large data sets, using the wrong tool for the task, insufficient budget to complete the analysis, not allowing enough time for testing and experimentation (the science), focusing too much on building the model (the engineering), not learning from the data, our assumptions, our preconceptions, and our skill. This paper will explore the question of how training regression models to predict rock density are affected by gaps in the data (missing observations and missing variables). What could possibly go wrong?

May 24, 2023

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 Yu A. B

An experimental study of the packing of a coal heap has been carried out. The bulk density of a coal heap is considered as a function of a number of variables, viz flow rate, conveyor belt speed, the height of the disengagement point of the conveyor belt, coal particle density, moisture content, the size of the heap and coal particle size distribution. The effects of the dimensionless numbers resulting from dimensional analysis on the packing density of a coal heap have been experimentally examined and analysed. Based on the experimental results, equations have been formulated for the estimation of the bulk density of a coal stockpile. The validity of these equations are checked by comparing the predictions with measurements of real industrial Stockpiles.

Jan 1, 1991

By R Bunduwongse

The oil crisis had repercussions throughout the world and most importantly on mining, where the drive to reduce the use of liquid fossil fuel led directly to the appearance and subsequent growth in the design of mobile crushers in late 1970s early 1980s, which heralded a new era in both quarrying and mining. Even though mobile crushing has now become common, even preferred in the quarrying industry, this has not been the case in mining. This paper looks at why, in spite of the initial optimism, this technology has yet to gain full acceptance in the mining industry. The paper examines some of the problems that have been encountered in the past and offers suggestions as to how they can be avoided by applying the appropriate technology. It then takes a look at the successful application of the semi-mobile in-pit crushing system used by Italian Thai Development Company (ITD), on the Mae Moh Phase 5 contract and examines how the techniques used successfully there could be applied to the industry at large.

Jan 1, 2007

By D Ford

BHP BillitonÆs new rotary iron ore car dumper installation at Finucane Island (Port Hedland) was constructed to increase the total capacity of the port facility from 110 Mtpa to 120 Mtpa and to allow for incremental capacity increases in future. The arrangement of the dumper is similar to other car dumper installations existing on site. To construct the facility, approximately 120 000 m3 of material was excavated in six months, to a total depth of 22 m. The saline water table was nominally 6 m below ground level and the materials excavated varied depending on depth, ranging from sand to mangrove muds. There was a need to retain the sides of the excavation and limit the amount of water from entering the excavated area. This was required to allow excavation to progress and had to be maintained during construction of the permanent concrete and steel facility. The excavation was backfilled progressively as construction progressed. Various retaining wall methods were investigated with the preferred option being sheet piles secured by walers and ground anchors. Detailed electronic models were developed and assessed to complete the final design arrangement. Dewatering bores around the perimeter of the excavation removed the groundwater to intercepted sumps within the site. A strict and methodical program was developed to monitor the integrity of the temporary works and the quality of the groundwater. The works were completed on time despite the following challenges being encountered: availability of resources and equipment, movement of mobile plant on æboggyÆ materials, difficulty driving sheet piles into material at depth, drilling of ground anchors to 32 m, grouting of ground anchors, greater than expected groundwater flows, and the risk of hydrocarbons within the groundwater. The lessons learned from the use of the retention system and, in particular, the associated construction challenges overcome, provide a sound basis for similar work in this buoyant resource market. The conference paper describes the temporary works options investigated, design considerations and processes, construction methodology and challenges encountered, and the monitoring systems developed. Lessons learned are also discussed.

Jan 1, 2007

By H F. Yu, S Ueda, J Diao, W F. Gu, Y Sasaki, H Qin

The main reason for the underutilisation of steelmaking slags is their instability, which is influenced by their complex phase structure. Recycling and sustainable steelmaking slag face challenges due to the presence of magnesium oxide (MgO), a crucial component in steelmaking slag. This study investigates the phase evolution of steelmaking slag during the cooling process with different MgO contents, using high-temperature experiments and FactSage™ software, ver 8.1, (by Thermfact/CRCT and GTT-Technologies) thermodynamic equilibrium calculations. X-ray diffraction (XRD) and scanning electron microscope - energy dispersive x-ray spectroscopy (SEM-EDS) analyses identified main phases in steelmaking slag, including Ca2SiO4 (C2S), RO (MgO-FeO solid solution), Ca2Fe2O5 (C2F), and Ca3SiO5 (C3S). The study reveals that RO phase increases as the MgO content increases. C3S precipitates from steelmaking slag with a 12 mass per cent MgO content at a reduced temperature of 1400°C. It is important to note that C3S remains in the steelmaking slag even after slow cooling. This may be due to the substitution of Ca2+ in C3S by Fe2+ and Mg2+ ions. Intriguingly, the precipitation of f-CaO in steelmaking slag with 10 mass per cent of MgO content occurred after one year, while there was no manifestation of f-CaO precipitation in the steelmaking slag with 12 mass per cent of MgO content even after one year. This discrepancy suggests a potential stabilising effect of an appropriate amount of MgO in steelmaking slag. However, it is crucial to emphasise that this inference lacks supporting data, necessitating further research to validate this hypothesis. The significance of this work is in uncovering the complexities of steelmaking slag behaviour, providing essential insights for optimising recycling processes. The research sheds light on the factors that influence the phase composition and stability of steelmaking slag, contributing to the utilisation of steelmaking slags, promoting environmental sustainability, and enhancing the overall efficiency of metallurgical processes in the current industrial landscape.

Jun 19, 2024

A recoverable uranium resource, shown to be suitable for in situ leaching, was discovered at Honeymoon in South Australia in 1971. Exploration of the deposit was carried out during the period from 1973 to 1979. Uranium mineralisation occurs in a coarse-grained unconsolidated sand aquifer located in the Yarramba Palaeochannel at a depth of approximately 110 m. Following initial development during 1979 to 1983 and the construction of demonstration leach facilities, the Project was put on hold. Southern Cross Resources purchased the Project in 1997. Government approval was received in March 1998 for the operation of on-site demonstration leach and recovery facilities while an Environmental Impact Statement was prepared and a 1000 tpa commercial production plant was designed. The Environmental Impact Statement (EIS) was released in June 2000 and operation of the test facility was completed in August 2000. Acceptance of the EIS by Commonwealth and South Australian state governments was announced on 20 November 2001. A Mining Lease was granted over the area of the proposed ISL operation on 8 February 2002. Operation of the Project is entirely dependent on using highly saline underground water resources to supply process and human needs. The management of discharge streams from the plant by re-injection was approved. The Honeymoon demonstration plant was the first adaptation of the solvent extraction process to highly saline in situ leach solutions. As such, it incorporated a number of unique operating and installation features. The trial period enabled optimisation of the process chemistry, additives and management and serves as an invaluable base for the proposed plant design and future operation. This paper discusses the nature of the uranium occurrence, the effect of saline water on the leach process and equipment, project design and environmental considerations, the requirements for disposal of discharge streams to minimise the impact on the arid environment and the requirements for rehabilitation following project completion.

Jan 1, 2002

By L N. Loganathan

Risk exposure in tunnel projects is extremely high due to various factors such as variability of subsurface conditions, selection of inappropriate design and tunnelling methods, improper risk assessment on adjacent surface and subsurface structures and utilities, and inadequate contractual practices. The risks in tunnelling must be borne by the contractor, designer and the owner of a tunnelling project. There have been a number of improvements in the last ten to 15 years in the manner in which tunnel projects are developed and implemented in terms of their design, construction, financing and operations. One significant improvement has been the manner in which underground conditions and their risks are being managed. Owners are less willing to transfer the full responsibility to the contractor for managing the underground conditions, although this is a familiar manner in which underground major urban projects have been previously contracted and managed. The owners of tunnel projects in Singapore have advanced the risk management process for their projects through geotechnical interpretative baseline reports (GIBRs), geotechnical data reports (GDRs) and project specifications (PSs). This paper discusses industry practice and its development as well as the application during the preparation and use in Singapore on the Deep Tunnel Sewerage System (DTSS) and the Marina Coastal Expressway (MCE) project in Singapore. The DTSS trunk sewer is 48 km and ranges from 3.3 m to 6 m finished diameter up to 50 m below the ground. The underground conditions ranged from Old Alluvium, strengths of about 1 MPa to competent Bukit Tima granite, with strengths of over 230 MPa. The total route length of the MCE is about 5 km. About 3.6 km will be constructed underground, consisting of dual five-lane carriageways. The underground construction will be cut-and-cover, and 2.6 km will be constructed about 13 m underground, and 1 km of tunnel will range from 13 m to 24 m as the tunnel passes under a 420 m wide reach of Marina Bay, whose crossing will be constructed as a two-phase cofferdam.

Jan 1, 2008