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By Gibson G, Jaques L

The Broken Hill Exploration Initiative (BHEI) is a collaborative venture between the Australian Geological Survey Organisation (AGSO), Mines and Energy South Australia (MESA) and the New South Wales Department of Mineral Resources (NSWDMR) to provide a new generation of geoscientific information to promote and enhance the exploration for, and discovery of, new deposits in the Broken Hill region. The area under investigation (Figure 1) exceeds 150 000 square kilometres on either side of the NSW-SA border and is centred on the city of Broken Hill. N.T. I I OL n. WA 8A I Maw. AC,7 !ii oFCU vlc~ ~T. Fia I - Nlap showing the 150 000 square kilometre regwa,. i.i lcr investigation by the Broken HiII Exploration Initiauvr highlighted on the map of Australia. A major impediment to the exploration for, and to the understanding of, the genesis of the world-class Broken Hill Pb-Ag-Zn deposit is the structural and metamorphic complexit\ of the region. Important objectives of the BHEI are therefore: I. the definition of the three-dimensional structure of the province, 2. the deformation history, and 3. the stratigraphic and age relationships of the rock units. Early discussions between the BHEI partners and industry scientists revealed that new geophysical surveys would be a key requirement to help advance the understanding of the province, especially a contiguous high resolution airborne geophysical dataset covering both outcrop and areas of shallow surficial cover. The purpose of this paper is to draw attention to the new high resolution airborne geophysical data and to discuss their interpretation and potential for enhancing the knowledge of the Willyama Supergroup geology.

Jan 1, 1997

By F Clark, M Erickson, J Biggam

Unraveling geological complexity and understanding geological risk are critical components of the challenge that face any mining or exploration venture. This understanding is essential to the successful selection of mineralised domains on which grade estimation relies, so knowledge of the geological characteristics of the mineralised domains is vitally important. æNuggetyÆ mineralisation introduces a higher level of risk and geological observation and intuition may be the only option to ensure that opportunities are realised and ore/waste characterisation is undertaken successfully. Mineralisation at the world class Sunrise Dam gold mine contains a significant coarse gold component, which has necessitated the development of a systematic visual approach to decision making that enables geological staff to determine the potential gold grade in the absence of assay results, and in those instances when assay results appear implausible. The development of the Mineralisation (MZ) Code at Sunrise Dam has assisted in reducing the risk of misclassifying ore as waste and enabled geological control to prevail with confidence where complexity and ambiguity existed.

Jan 1, 2009

The C.S.A. copper lead zinc mine, located seven miles north of Cobar in Central Western New South Wales, is the largest known mineral occurrence in the Cobar Mining Field. Hosted by the steeply west dipping, west facing sediments of the Cobar Group, the generally discordant orebodies occur within a strike width of 600 ft and an overall strike length of 1200 ft. They comprise lenticular steeply north pitching and east dipping zones of sulphide mineralisation which range in composition from massive pyrite-sphalerite-pyrrhotite--galena to less massive pyrite- pyrrhotite-chalcopyrite varieties. The thinly bedded siltstones, shales and graywackes hosting the mineralisation appear to have derived many of their constituents from volcanic sourcesä They have been metamorphosed to the greenschist facies of regional metamorphism. At least two stages of deformation and folding have occurred. The first stage folded the rocks on a south pitching fold axis into their present configuration, and super- imposed a strong axial plane cleavage which subsequently guided the emplacement of the mineralisation. The second stage of deformation is considered to have controlled the zonal distrib- ution of the orebodies and the appropriate fold axis appears to coincide with the long axis of the orebodies.

Jan 1, 1969

By M J M Cunningham, M Greentree, J H Liu

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. The Palaeozoic rocks of north-eastern Laos are an attractive target for gold explorers due to the complex tectonic history and lack of past exploration in the region. Alluvial workings along the Nam Xiang River and its tributaries have highlighted the potential for gold mineralisation in the Vieng Kham region. The Nam Xiang River follows a regionally-extensive NNE-striking thrust fault. Adjacent to the Nam Xiang fault, the dip of the main foliation steepens, and in many places the stratigraphy is overturned as a result of this faulting.United Minerals and Mining Company conducted a regional exploration program to explore for gold. This included stream sediment and rock-chip sampling, and airborne geophysics. Geochemical anomalies were followed up with more detailed exploration, including geological mapping and soil sampling. Despite the relatively deep weathering profile, gold mineralisation is associated with a low-level but well-defined gold-in-soil anomaly. Drilling has shown that gold mineralisation occurs on structures and fabrics parallel to the main Nam Xiang fault. The highest gold grades are associated with brecciated sandstones that have experienced strong carbonate alteration. This suggests that late-stage structures such as the Nam Xiang fault are the major control on gold mineralisation in the region.CITATION:Greentree, M, Cunningham, M J M and Liu, J H, 2015. Gold mineralisation along the Nam Xiang fault, Vieng Kham Project, North-east Laos, in Proceedings PACRIM 2015 Congress, pp 177–182 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

A biological column leach testwork program was undertaken on a chalcocite ore. Three tests were conducted in all, using 65 in x 100 mm columns in three sections. The tests were started with varying acid strengths and inoculated with bacterial solutions from previous column testwork. The leaching of Cu was found to occur in three stages. These stages consisted of direct acid leaching, bacterial oxidation and ferric iron leaching. These leaching stages can most easily he described through the examination of not only Cu dissolution but also Fe dissolution and its subsequent oxidation and precipitation. The p11 of the system was found to he critical in establishing and maintaining the bacterial leaching system. The oxidation potential was seen to he influenced by the leaching system as the oxidation states altered. Test variables such as, 02, COz, and temperature were all found to influence the system. Final copper recoveries were in excess of 90 per cent in each column test over a leach time ranging from 211 to 328 days. Given similar leach conditions are applied, the application of this technology to site is expected to give comparable results.

Jan 1, 1994

By OÆGrady P

Finite element analysis is becoming a routine component of design of longwall extractions, now superseding more traditional somewhat intuitive approaches. Finite element modelling is relatively inexpensive and provides an adequate degree of similitude to give satisfactory analysis. The physical modelling of two decades ago is now largely replaced by numerical methods of which finite element is the best known. Important data for finite element work are physical properties, including creep aspects, introducing the non-linearity of stress response.Various computer packages are available and some were used to model two specific UK examples, using both linear and non-linear approaches. It appears that non-linear approaches will yield most benefit. The use of materially non-linear analysis is merited by the greater similitude it provides between model output and real mine situations.

Jan 1, 1991

By M M. M LT Tassinari, A B. Braz, L M. SantÆAgostino, C Ulsen

Several mineral resources have been recognised to alkaline igneous rocks. In general, these mineralisations present low P grades, so a complex concentration process is required to achieve commercial grade concentrates. This process is guided not only by the ore characteristics, such as apatite grain size and liberation degree, gangue minerals and slimes content, but also by different apatite varieties, iron oxi-hydroxide surface coating and roughness. The main techniques applied to apatite and phosphate ore characterisation, such as optical microscopy, cathodoluminescence (CL) microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), surface techniques and magnetic separation are discussed, aiming to evaluate distinct apatite varieties and their technological behaviour.

Jan 1, 2008

This paper presents a new idea in field data collection for geological and scientific data. The computer keyboard has been replaced by a barcode wand driving a spreadsheet style editor. To use the full capabilities of computer hardware currently available, geotechnical and geological data can be entered and validated in the field, in a structured format, for later transfer into modem geological modelling databases. An example, using a geotechnical borehole log, explains the principles discussed. The generic nature of the Datcol system is illustrated by the application developed using the Norwegian Geotechnical Institute Rock Mass Classification system. A brief description of a modem spatial relational database is also given with particular reference to underground engineering.

Jan 1, 1993

By Sehic O. A

Geology can be the root of evil or a source of bliss; there is a choice; to ignore geology is at a mine's peril.Risk can be minimised and profitability maximised by the application of a detailed understanding of geology, alteration, structure, mineralogy, chemistry, fabric and texture.Geology is dynamic, not static.The impact of geology is pervasive.The integration of ore quality control with grade control is one strategy for improving the utilisation of both the mineable reserves and existing plant and equipment. Grade maintenance is but one constraint on the problem of how best to blend the ore. Other ore characteristics such as mineralogy, hardness for grinding, and pulp fluidity or density for slurry size classification can be included to explore alternative blending Strategies.

Jan 1, 1993

The paper describes developments since 1959 in major excavators to meet the demand for higher outputs of overburden and coal under less favourable batter conditions than used hitherto in the coal deposits of the Latrobe Valley. Particular reference is made to investigations of designs of bucket wheel head configurations for the digging of these flat batters on high faces, and examples are given of the wide use of models inthese studies. An explanation is given of how solution of these problems and surface conditions unfavourable for wheeled transport confirmed selection of the long boom rather than the compact type of bucket wheel excavator for the Latrobe Valley applications.The past decade has seen advances in the manufacture in Australia of components for excavators and similar machines. The history of Australian manufacture of components for major brown coal excavators is traced;and reference is made to study and application of Australian and overseas (mainly German) codes and practices in the design and construction of machines made partly here and partly in Germany.A section of the paper deals with advances in electrical engineering for large excavators in Australia and its interdependence with mechanical design and construction.Finally, as an example of the versatility of the bucket wheel excavator, a description is given of a recent application for the mining of mineral sands in northern N.S.W.

Jan 1, 1971

By P Dare-Bryan

Many mines have an interest in improving fragmentation at their sublevel caving operations in order to produce better ore recovery, lower dilution and less overbreak. The primary requirement for the extraction phase is to understand and optimise the flow of the fragmented rock in the rings including interactions with the caved material. Rock fragment formation is critically controlled by the blasting phase and can potentially be improved by optimising the dynamic energy distribution throughout the ring through the crafting of explosive charging, priming position and initiation timing. The modelling of fragmentation and damage due to explosive loading of complete rings is inherently and irrevocably a three dimensional problem that is difficult to address. We have therefore initially utilised an analytical code to predict vector peak particle velocities and energies that are restricted to the plane of a ring. Dynamic energy distributions based on common timing and priming practice have been compared with other possibilities using conventional pyrotechnic detonators as well as initiation designs based on accurate electronic detonators. The energy distribution can be quite subtly tailored to increase energy in appropriate regions or to decrease energy in the brow region for example to potentially reduce instability and the probability of misfires. We have also recently developed the capability to efficiently model particle flow using four-sided polygonal elements. Despite the 2D limitations of such a model this results in more realistic fragment interaction and stacking than can be achieved using conventional rigid circular elements. Modelling of a typical sublevel caving ring utilising these elements activated by the correct dynamics offers considerable potential for understanding the influence of the blasting energetics and timing on the complex flow and extraction process.

Jan 1, 2005

A system for rapid on-line determination of weight percentage coal in slurry and weight percentage ash in coal has been developed at the Julius Kruttschnitt Mineral Research Centre, University of Queensland. The gauging system is suitable for use with coal flotation slurries or slurries having a maximum particle size of about 1 millimeter. The system is based upon measurement of gamma ray transmission; radioisotope sources emitting photons of two widely different energies are employed. The inaccuracies of measurement that would normally result from variable amounts of air entrained in the slurry are substantially reduced by pressurising the slurry to approximately 2MPa (300 psi) using a Mono pump. The equipment can be used to make measurements on more than one slurry stream by pumping streams sequent- ially. The system is being tested at the Peak Downs Mine of the Utah Development Company in Central Queensland. This paper describes the theoretical principles of the gauge design, the experience gained to date in the commissioning of the equipment, including the installation of a PDP 11/03 computer, and the progress made in developing satisfactory interpretations of the gauge count-rate output.

Jan 1, 1978

By S Long, A J Koen, D MacKay

The Mt Wright Underground Mine is located near the town of Ravenswood in North Queensland and is operated by Carpentaria Gold – a wholly owned subsidiary of Resolute Mining Limited. Following the evolution of the mine plan through a number of stages, the ‘sublevel shrinkage (SLS) with continuous fill’ mining method was implemented in 2010 to extract the Mt Wright orebody. The production front in this mining method is similar to a sublevel cave (SLC) operation; however, backfill is placed into the top of the production zone as opposed to requiring the overlying strata to cave.Continuous fill to replace the void created by extracting the ore was required to manage the potential risks associated with the proximity of infrastructure to the footwall, associated long-term stability and air blast potential due to the limited ‘cavability’ of the material within the cave zone. The available fill material was sourced from a disused waste dump from a previous open pit operation, which introduced further technical and economic risks associated with dilution from ‘no grade’ broken material. Procedures and processes to manage these risks have been incorporated into the operation of the mine.Despite encountering a number of challenges, the SLS method has been in use for approximately three years at Mt Wright and has proven to be viable economically, technically and operationally. This paper will discuss the challenges encountered and what was done to overcome them, the operational and financial performance to date, along with the outcomes of some successful continuous improvement projects that have improved the efficiency of the operation.CITATION:Mackay, D, Long, S and Koen, A J, 2014. Sublevel shrinkage – the Mt Wright story, in Proceedings 12th AusIMM Underground Operators’ Conference 2014 , pp 205–216 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 24, 2014

Zinc concentrates from the newer mines and from proposed developments provide both opportunities and processing challenges to the conventional roast-leach electrowin smelters. These concentrates are often characterised by low iron, elevated silica, possibly high manganese, and levels of elements such as germanium which may cause concern. In addition, environmental constraints on residue disposal are forcing significant changes to some smelter practices. Iron in concentrate, and the resulting environmental impact of residue disposal are now major questions. However, normal concentrate tariff structure provides a disincentive against smelters taking high grade concentrate and oxide fume. Processing technology to cope with these changes is reviewed, as is de-watering and materials handling of ultra-fine concentrate. Within a few years, such fine concentrates will account for up to 1 000 000 t/y of contained zinc. New processing technologies including novel transport methods, siliceous leach circuits, manganese removal cells and front-end smelting will become significant in zinc smelting.

Jan 1, 1993

By P Voulgaris

The Osborne Mine commenced production from an open pit in December 1994 with the first ore being hauled from underground one year later. Currently all ore is hauled up a decline by trucks until the shaft system is commissioned in early-1998. The mine is hosted within a multiply deformed and complex sequence of metamorphic, igneous and metasomatic rocks of mid Proterozoic age that are concealed beneath 20-40 metres of Mesozoic sedimentary cover. Epigenetic and largely hypogene copper - gold mineralisation occurs in a close spatial relationship with quartz - magnetite ironstones and is an important example of a significant mineralisation style in the Mt Isa inlier. Life of mine concentrator production, to year end 1997, totals 3.2 Mt of ore at 3.40 per cent Cu and 1.13 g/t Au. Total metal produced was 97 000 tonnes of copper and 2900 Kg of gold (95 600 oz) from some 348 000 tonnes of dry concentrates averaging 28.01 per cent Cu and 6.99 g/t Au. At the start of 1998 OsborneÆs total measured and indicated resource was stated at 11.38 Mt at 3.24 per cent Cu and 1.21 g/t Au with an ore reserve of 11.42 Mt at 2.90 per cent Cu and 1.09 g/t Au. Exploration efforts in and around the mine have been increased since 1996 and have resulted in an early success, with a 28 per cent increase in ore reserves since mine start-up, and the establishment of a 1.5 Mt inferred resource open to depth. During 1997 the performance of the concentrator has exceeded expectations with throughput having been increased to 1.45 Mt per annum. The Mining Cycle at Osborne has proceeded from discovery through feasibility and is currently seen to be in the latter part of the development stage and/or the early part of an expansion stage. This paper will describe the role of geology and exploration within these stages and will highlight how a number of key interpretations and decisions based on geology have both favourably and unfavourably affected the project.

Jan 1, 1998

By Firmin K

The Mt. Tom Price orebody of Hamersley Iron Pty. Limited consists of a folded hematite - shale sequence capped by a layer of goethite. Consequently, variations in iron content occur within the orebody, and as the overall grade is below that required to make specification products, selective mining must be carried out. A necessary preliminary to quality control'of products based on selective mining is the production of advance data, on the tonnages and grades of material to be expected in future mining areas. Bench plans showing zones of different grades and types of material anticipated are prepared from structural geological information. The grades of materials on a bench are essentially governed by the positions and attitudes of the shale bands. Quality control is exercised by blending different grades and types of material in primary crusher feed. Iron grade is the prime grade consideration although sometimes the level of phosphorus content must be considered. Pre-production grades Are determined from assay of samples taken from blasthole cuttings.

Jan 1, 1980

By O Dahl, I M. Platten, E J. Sides

Many narrow-vein gold deposits are characterised by a high to extreme nugget effect and the presence of coarse gold. They rank amongst the most difficult of deposits to produce an accurate and precise resource estimate. This contribution presents a case study from the Nalunaq Gold Mine in Southern Greenland. The mine commenced operation in May 2004 and is currently operating at a rate of 400 tonnes per day, to produce about 100 000 oz gold per annum from a total resource base of 1.2 Moz. Mineralisation is characterised by quartz veins that are hosted within a shear zone that is continuous over about 1000 m. The principal orebody is the Main Vein structure, which ranges up to 3 m in width, maintains an average dip of 35¦SE, and contains significant gold grades (1000s g/t Au). Gold particles are often visible, with 25 per cent being greater than 250 microns in size. Variography using underground development samples indicates a nugget effect of about 75 per cent. For the 2005 resource estimate, a 2D metal accumulation ordinary kriged block model was used to produce a global grade for the Target and South Blocks of the Main Vein. Grade control chip-channel samples are collected from æshantyÆ drive footwalls, and used as the basis for both the kriged block model and to determine the grade of individual stope blocks by peripheral weighted averages. Geology plays a key role in mining efficiency, given the locally variable nature of the ore zone.

Jan 1, 2006

By D S. Clarke, K B. Sporli

Structure is an important control in the localisation of gold mineralisation in epithermal systems. There has been, however, only limited investigation of the structural elements involved; such a study is currently directed at the gold deposits of the Coromandel Volcanic Zone (CVZ). Here, mineralised veining and brecciation ranges up to tens of metres in thickness. Dips of veins are mostly steep, but not vertical, and there is a significant number of low angle veins. The structural control of epithermal deposits may be considered on four scales. At the mega-tectonic scale, pre-volcanism fault patterns mostly relate to separation of the New Zealand micro-continent from Gondwana. The major structural controls on mineralisation at this scale, however, are associated with the volcanic arc processes responsible for the CVZ. Post-mineralisation faulting are linked to the Hauraki Rift and the Colville Ridge-Havre Trough system. Regional scale faults controlling the distribution of gold deposits are the product of these tectonic events; much of the faulting may relate to rifting and calderas, but further work is required to demonstrate this. Detailed study is also needed on vein systems at the prospect scale to validate models of brittle deformation responsible for such systems. Evidence that a variety of structural mechanisms dominated in different deposits is found at the vein scale, with Coromandel gold deposits being classified according to their different styles of vein-fill texture.

Jan 1, 1990

By L Whitbourn, K Yang, P C, E Ramanaidou

The potential of hyperspectral mineral mapping within a mine environment is demonstrated. Central to this capability has been the development of portable or vehicle-mounted, hyperspectral mine face-mapping systems. Data from these systems were used to detect subtle mineralogical variations and map their distribution across rock faces in a fashion that previously was not possible. In one study, the data usability was enhanced by ædrapingÆ the mineralogical determinations over a three-dimensional æmodelÆ of the rock-face. The eventual melding of the spectral mine face-mapping and three-dimensional spatial technologies will result in a new generation of mineralogical and structural information becoming available to mine geologists, engineers and metallurgists. Specific uses for spectrally-derived, mineral mapping data sets could include:ore grade mapping systems based on either direct detection of ore minerals themselves (eg iron and nickel oxides), or mineralogies that may be used as surrogates for ore-grade information (via various alteration minerals) after a suitable orientation survey; detecting mineralogies that have a deleterious effect on milling, metallurgical processing or have occupational health implications (talc, swelling clays, carbonates, asbestos, etc); selective mining and blending by collecting, processing and displaying such mineralogical images in near real-time to monitor ore grade and quality, and allow the separation of ore from waste during loading operations at the mine face; a mineral detection and mapping capability to assist in structural and geotechnical mine planning applications; and an enhanced geological detection and mapping capability for ore mineral species or alteration mineralogies that may be used to vector further mineralisation, update the existing mine ore model, or provide input to assist in the control of autonomous mining equipment. Within the Woodlawn open pit, Fe- and Mg-chlorites and phengitic- micas associated with sulfide mineralisation were detected and mapped. Subsequent studies using a second generation face-mapping system demonstrated the direct detection of ore-grade materials for iron-ore and nickel laterite mining activities. Satisfactory and meaningful results were extracted from data that were collected under a variety of challenging conditions. However, these non-ideal climatic and operational conditions would be expected under most operational situations in a mine environment. Development of a system using artificial illumination, permitting night-time (and eventually underground) operation and elimination of atmospheric absorption effects is underway.

Jan 1, 2006

By C Philander

The West Coast of South Africa is well known for its placer gem quality diamond deposits and also associated with these hosts of Cenozoic unconsolidated marine and aeolian sand and gravel are significant concentrations of heavy minerals. Exploration for economic concentrations of zircon, ilmenite and rutile along the coast started in the mid-1980s. This resulted in the discovery of an inferred 1.6 billion tonne resource with a grade of ten per cent total heavy minerals (THM), which developed into the Namakwa Sands Mine, a world-class producer of heavy minerals. Several other resources, including satellite deposits proximal and distal to the mine area, extensive diamond mine dumps and present day beach placers, demonstrate the vast heavy mineral potential along the West Coast. The favourable gangue to economic mineral ratio, a higher zircon content compared to other similar deposits, relatively lower U+TH content of zircon, low slimes content and effectively pristine low chromium-manganese ilmenite of these deposits, render them attractive exploration targets. Negative factors that will affect conventional mineral beneficiation and liberation include secondary mineral coatings and the regional coastal development of several layers of superimposed duricrust. The economically attractive heavy mineral assemblage along the West Coast is the result of erosion of the proximal, gneissic Namaqualand Metamorphic Province and mature Table Mountain Group sandstone, concentration by marine and aeolian processes and preservation under arid climatological conditions over a period of more than 100 Ma.

Jan 1, 2008