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By D Lau

Traditionally X-ray diffraction (XRD) has not been significantly used by the cultural heritage sector, as the most commonly used technique, X-ray powder diffraction (XRPD), requires sample removal from the artwork or artefact, followed by grinding of the sample to a fine powder. With the development of micro-X-ray diffraction (micro-XRD) and other associated advances, non-destructive, in situ analysis of crystalline pigments on micro-areas of paintings and artefacts has become possible. This is illustrated with the application of this technique to the in situ analysis of propriety paints, paint cross-sections and small paintings. However, workers have noted that XRD can be insufficiently sensitive with pigment mixtures, due to matrix effects. This study obtained X-ray diffractograms of 17 single pigment preparations and determined relative amounts of crystalline content. The purity of single pigments was compared with Joint Committee on Powder Diffraction Standards (JCPDS) database diffractograms. The impact of pigments with high X-ray absorption coefficients on the detection limits of pigments with low X-ray absorption coefficients was further investigated by building on work done with the chromium oxide-zinc oxide series with the preparation of a second series of binary mixtures of zinc oxide (which has a high absorption coefficient and is almost fully crystalline) and ultramarine blue, which has a lower absorption coefficient but which is more crystalline. Semi-quantitative analysis, where baseline and absorption factor corrections are made, confirm detection limits as low as five per cent for chromium oxide and ultramarine blue when in a binary matrix with zinc oxide. However, this type of analysis is very time consuming. So in order to theoretically simulate issues that will be encountered with binary pigment mixtures, the single phase diffractograms were used to theoretically investigate the matrix effects of the three white pigments with the various coloured pigments. This illustrated that detection limits can be as low as five per cent or in non-ideal conditions, such as with partial peak clashes or where there are large differences in relative peak intensity, as high as 50 per cent. These results have significant implications for the analysis of painted surfaces on artworks or artefacts. It has been demonstrated that ideally this method is more suited to the investigation of surfaces where there is minimal mixing of pigments or where there is not a significant difference between the absorption coefficients of the mixed pigments.

Jan 1, 2008

The electrochemical dissolution of gold and other noble metals in hydrochloric acid using alternating current has been investigated. The experimental results show that this technique is efficient for dissolving pure noble metals and offers prospects for their extraction from wastes and poor ores.

Jan 1, 1992

The difference between a hypothetical and a theoretical approach is considered and the advantages in using a hypothesis is discussed. Virgin horizontal stresses play an important role in stabilising strata which bridge across an excavation, and reduces the tensile stresses which develop in a beam subjected to bending. Simple formulae are deduced for the bridging of a thick massive stratum under such conditions. At shallow depths, tensile failure on the upper side of the beam is the most likely cause of fracture, but below a certain depth this gives place to compressive failure on the underside, with the possible incidence of rock bumps. The presence of strong massive beds delay the onset of subsidence and may restrict the width of the subsidence trough. If the material involved in the caving is strong, this will reduce the final subsidence, especially at shallow depths. The British regulations for the control of aquifers and their dependence on the strain developed at the seabed are discussed. As an alternative, the concept of a disturbance factor is introduced to permit the consider- ation of aquifers at depth, leading to an explanation of the make of water on the first faces to be mined in the Selby Coalfield. 'Elie paper closes with a brief consideration of the different roles played by longwall face supports in the control of readily cavable strata, and the control of strong beds which hold up in the waste.

Jan 1, 1986

By F Mwijage

"The benefits of measuring blast movement to reduce ore loss and dilution have been recognised by many people for many years and various methods have been used with limited success. Geita Gold Mine is running the pilot study on the blast movement monitoring (BMM) system which is a revolutionary method developed and patented by the University of Queensland and Blast Movement Technology (BMT). The system consists of directional transmitters placed within the shot prior to blasting, which are then located after the blast with a special detector and then the data is processed with purpose-designed software.As part of continuous improvement on grade control, Geita Gold Mine is running a research project in all operating pits with the objective of: quantifying the three-dimensional blast muck pile movement and finally utilise the movement data to define post-blast ore polygons and incorporate the movement dynamics during block modelling,quantify the potential savings for ore loss and dilution,improve mine geologists knowledge of blast dynamics, andstimulate greater co-operation between drill and blast engineers and geologists to achieve optimum blast designs.To any operation with selective mining, it is critical to the economics of an operation to control ore loss and dilution; getting it wrong will result in significant lost revenue. Implementation of ongoing pilot study on electronic balls as determinant on blast movement dynamics on ore would be of longer term solution and big investment pay back.CITATION:Mwijage, F, 2012. Pilot study on blast movement monitoring at Geita gold mine, in Proceedings Narrow Vein Mining 2012 , pp 49-58 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 26, 2012

By Fabjanczyk MW, Guy RJ, Tarrant GC

The design of the reinforcement systems required to stabilise mine roadways has developed through the application of field measurement techniques. These techniques have allowed the level of security of a given opening to be determined from an assessment of the loading within the reinforcement, the extent of roof deformation and experience. The design systems developed are now used extensively in a wide variety of geological environment. Recent interpretative techniques have been developed to improve the level of confidence when designing roadway reinforcement. The techniques are particularly applicable for roadways subject to either weak materials or extreme stress levels. A second area of application is where roadway advance rates and hence the timing of reinforcement placement are critical. The newly developed techniques include both analytical and computational models. The validated computational techniques allow a more rational approach to investigation of the effect of varying reinforcement type, timing of placement and density on the level of stability achieved.

Jan 1, 1992

By F Pothitos, S Hewson

The geological and geotechnical conditions at the Cadia Hill Open Pit are very complex. This complexity coupled with high mining rates has required significant technical input into the design and optimisations of the pit slopes, accesses, cutbacks and scheduling. A multi-discipline team of NML engineers, geologists and external consultants has been conducting comprehensive geological and geotechnical programs in order to achieve an optimum design of the pit slopes. Extensive data collection, analysis and interpretation has led to the formation of working geotechnical models of large structures, rock masses, and back-analysed slope performance charts. The current Cadia Pit Optimisation Project focuses on the risk-and-return principle for pit design and on the integration of geotechnical, hydrogeological, mining engineering and scheduling. The risk management for pit design has also been incorporated into the short term and long-term operation of the pit mining to ensure safety and production.

Jan 1, 2003

Tailings facilities tell a story to the public about how the mining industry manages its activities. They also create a risk that must be managed for the long term. All the knowledge and technology is available to safely design, build, operate and decommission tailings facilities.   Tailings at Waikato North Head Minesite are pumped as slurry, over long distances and against high static discharge heads to backfill the excavated area. WNH is, under the mining licence, obliged to reconcile the topography of mined areas to the closest possible resemblance of the original terrain. The active tailings areas are located near main operational facilities and detailed plans and procedures have been developed to ensure a safe and continuous operation.   The concentration plant is designed as two identical and independent plants. Each plant has its own tailings slurry pumping system.   This paper represents a general overview of the tailings disposal practice at WNH mine site. It discusses tailings delivery, construction and water management.

Jan 1, 2004

AXTAT is a computerised system developed by the Western Australian Department of Minerals and Energy in conjunction with the local mining industry for recording and retrieving information about fatalities and work related injuries. Since its inception, the system has gained considerable recognition by consistently demonstrating its usefulness as a tool, not only to the Department, but for the entire industry nationwide. AXTAT has played an important role in the continuous improvement process in management of occupational health and safety in the Western Australian mining industry with gains in both human and financial terms, by regularly providing timely and accurate statistical feedback on fatalities and lost time injuries to industry.

Jan 1, 1996

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

By Waller M. D, Whittaker B. N, Singh R. N

This paper overviews the recent research progress in predicting cutting performance using fracture mechanics principles. It is emphasised that rock fragmentation due to cutting is mainly a process of chip formation resulting from crack initiation and propagation or crack interaction for multi-tool cutting. This process can be simulated by using the well developed fracture mechanics criteria coupled to numerical methods. Fracture toughness is shown to be an important and useful parameter in quantifying cutting performance and in designing cutting tools. The paper concludes with discussions on the dynamic effects involved in rock cutting processes which should be taken into account for optimum cutting efficiency and tool design.

Jan 1, 1992

By J M. Palin

Hydrothermal scheelite precipitated in fault-veins at Paradise, Bonnie Jean, Davidson's and Glenorchy mines display chemical variability involving REE patterns that are transitional between two end-member types. Type I is a MREE-enriched pattern with no or a small positive Eu anomaly. Type II is a flat to MREE-depleted pattern with a strong positive Eu anomaly. The chemical inhomogeneity of these scheelites can be explained by a model of fractional precipitation of REE, with preferential removal of MREE from the fluid during precipitation of scheelite. Irrespective of the mechanism responsible for scheelite precipitation, the source of dissolved constituents is different for scheelites from the Paradise Mine. Bonnie Jean, Davidson's and Glenorchy scheelites formed from LREE-enriched fluids whereas Paradise scheelites precipitated from fluids that were lower in LREE. These inferred fluid characteristics cannot be linked unambiguously to specific source rocks in the region, but could suggest that scheelite deposited in the Paradise fault-vein reflects a more mafic source of REE possibly greenschists, whereas the REE in scheelite from the other mines suggest a more felsic source.

Jan 1, 2003

Some important mineral fields are referred to in discussing the formation of placer deposits in Australia. Testing methods include boring hand, with percussion rigs; with auger and pit digging drills; and l by vibro drilling. Sampling errors are minimized by the use of correct techniques and equipment for boring, sampling, and sample dressing, A hypothetical set of data is used to demonstrate the final process of evaluation, and some relevant taxation provisions are discussed.

Jan 1, 1964

Gold mineralization belt of eastern China in the adjacent part of the northwestern Pacific rim is orientated NE to NNE and as-sociated with Mesozoic faults and igneous intrusives and Mesozoic to Cenozoic volcanism and subvolcanism extending more than 3000 km in length and 300 to 800 kni in width affected by the movement from the Pacific Plate subducted against the Asian Plate.The relative movement between the Pacific and the Asian plates give rise to two types of fracture zones, the tensional ones providing the space for the formation of fissure-filling type of auriferous quartz veins and the shear zones providing the space for the formation of hydrothermal replacement type of gold de-posits in Shandong Peninsula. The fissure filling type of quartz vein, is represented by Linglong gold deposit which is hosted in Mesozoic Linglong Granite and consists of hundreds of quartz veins filling fractures trending NE to NNE and the hydrothermal replacement type is represented by Sanshandao gold deposit which is hosted in crushed and hydrothermally altered Mesozoic Linglong Granite in contact with Archaean metamorphic complex of Jiaodong Group along a Mesozoic upthust fault zone trending NE.

Jan 1, 1990

By Yu AB, Azahari HL

Indonesia has the largest coal reserves in the south-east Asian region. According to estimates from the World Energy Confer- ence, it has reserves of 18 billion mt lignite, 4.4 billion mt sub-bituminous coal and 774 million mt bituminous coal (Wyllie,1988). In recent years, substitution of coal for oil in power plants has been the goal of the Indonesian government since proven deposits of coal are about five times as large as national hydrocarbon reserves and most of Indonesia's power stations are still oil fired. Recently a coal fired power plant has been built in Java Barat, which will have a full capacity of about 3000 MW. It is intended to supply coal for this power plant from Bukit Asam mining area (South Sumatra). Coals from Bukit Asam - which are of the lignite or brown coal type - usually contain considerable moisture . It should be noted that reference to moisture in coal pertains to the total moisture content. This is comprised of what is commonly termed as equilibrium moisture and surface moisture. Surface moisture typically affects combustion process as well as pulveriser performance since it possibly influences the relative ease with which coal may be ground. In practice, the surface moisture produces agglomeration of the fines in the pulverising zone and reduces pulveriser drying capacity because of the inability to remove the fines as quickly as they are produced. This agglomeration has also the same effect as coarse coal during the combustion process because the surface area available for the chemical reaction is reduced, hence the combustion efficiency is also reduced. The influence of the moisture of some coals on their grindability (Hardgrove Grindability Index) has been previously correlated by several authors; some of them will be mentioned later. Those correlations, however, could not be immediately applied to any coal since it is still believed that there are other factors which influence the grindability of the coal, such as type and rank of the coal. The relationship between coal moisture content and its grindability has been investigated by Ellmann and Belter (1955). It was found that, for North Dakota lignites, the grindability varied as the moisture content changed. In Britain, Fitton, Hughes and Hurley (1957) stated that, for Bilsthorpe coal, over a wide range of free moisture content (from air-dried to about 30 per cent moisture), the Hardgrove Grindability Index (HGI) remains virtually unchanged. In addition to that, it was suggested that it would be slightly advantageous to dry the coal below its air-dried moisture content (at temperature ¦ 100¦C) to increase the ease with which coal could be ground, especially for low-volatile coal and high-volatile non-caking coal. Furthermore, it was also concluded that a broad relationship appeared between coal rank and Grindability.

Jan 1, 1993

By Pathan AG

This research work is concerned with an investigation of the fracture toughness of sandstone, siltstone, and coal. Tensile failure trades have been examined with three different specimen geonetries, i.e; rectangular bar, round bar (in three point bending), and diametral compression discs. The Stress intensity approach, and J-integral methods were used to evaluate fracture toughness. Results from both approaches are discussed. True crack length was determined after pre-cracking, using the compliance calibration technique. Fracture toughness results of sandstone are independent of crack length and the size of the specimen. Fracture toughness may hence be regarded as a material property for sandstone. In cxnntrast fracture toughness values for !siltstone and coal are dependent on crack Length.

Jan 1, 1986

Mineral Sands - "An Industry for the Future"The mineral sands industry is matched only by the gold industry in relation to its current buoyancy. The strong demand for the various mineral sands products, creates a positive environment in which to review the technical and commercial factors affecting the future of this industry. This conference is clearly being held in the right place at the right time.My role today is to put forward a few ideas that may help Australia to assert its rightful role as a major downstream player in an industry which it has dominated for 25 years as a raw material supplier.

Jan 1, 1986

Over the past 15 years many world-class gold discoveries have been made in the region. Some deposits, such as Lihir and Porgera in P.N.G., have a contained gold resource that places them among the top dozen deposits ever found on a worldwide basis. Can we see any pattern to these discoveries, or are they the result of good luck or chance by geologists and prospectors who struck it rich? Whilst such discoveries were a feature of the gold rushes of the 1850s and the 1900s, the present boom is now scientifically based. This paper develops an argument that long-tent, multi-disciplinary exploration by experienced geoscience teams underlie the successes achieved. Dis- coveries nearly always reflect a combination of skills, drawn from the areas of geology, geochemistry, geophysics and remote sensing, and a team approach. They do not represent the chance finds of a prospector's pick or such as the Norseman discovery where the gold reef was first noted by the prospector when his horse fell over the outcrop. The following deposits provide major examples of exploration successes within the Australian-Pacific region, it is not an exhaustive list and I have noted other significant producers at the end of this paper. For the Australian mines listed and based on our estimates for 1990 gold production, they represent about 20 per cent of the Australian production total.

Jan 1, 1991

By D Schwab, R M. Tosdal

The Quesnell-Stikine arcs, in the Canadian Cordillera, are host to Triassic and Early Jurassic alkalic porphyry Cu-Au and calc-alkalic porphyry Cu-(Mo-Au) deposits formed outboard of ancestralNorth America in island-arc tectonic settings (McMillan, 1991). The majority of the alkalic porphyry Cu-Au deposits are products of a discrete magmatic event at the end of the Triassic, with a second and smaller event in the Early Jurassic (Mortensen, Ghosh and Ferri, 1995). Of the Triassic complexes, the Galore Creek alkalic intrusive suite is one of the largest and most silica-undersaturated intrusive complexes, and host to the most significant undeveloped alkalic porphyry Cu-Au resource in North America (Lang, Stanley and Thompson, 1995). Because of the common presence of feldspathoidal-bearing rocks in the complex (Enns et al, 1995), Galore Creek likely represents an end member example of the alkalic porphyry Cu-Au class. The Galore Creek alkalic Cu-Au-Ag porphyry district, located in NW British Columbia (Canada), contains 12 mineralised prospects (Enns et al, 1995; Micko et al, 2007; Schwab et al, in press) with a total measured and indicated resources of 785.7 Mt at 0.52 per cent Cu, 0.29 g/t Au and 4.87 g/t Ag (NovaGold Resources Inc, February, 2008). The Central Zone is the largest and best delineated. Other economically important mineralised centres include the South-West, Bountiful, West Fork and Junction deposits. The South-West Zone, the focus of this contribution, is a Cu-Au-Ag breccia-centred deposit with a measured and indicated resource of 69 Mt grading 0.42 per cent Cu, 0.69 g/t Au, 2.67 g/t Ag. Hosted in brecciated intrusive rocks, the South-West Zone is distinctly younger than the Central Zone and most of the other mineralised centres (Enns et al, 1995; Schwab et al, in press). The South-West Zone therefore preserves the late stages of hydrothermal evolution at Galore Creek. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By L O. ÆNeill, J Bebek

When Kalgoorlie Consolidated Gold Mines (KCGM) purchased its fleet of 18 CaterpillarÆs dump trucks in 1999, as part of its change to owner operated mining, five CaterpillarÆs Computer Aided Earthmoving Systems (CAES) were also commissioned on Komatsu PC8000 hydraulic shovels and Caterpillar D10R bulldozers. Since then the CAES system has been installed and operational on Komatsu PC3000 hydraulic shovel, CaterpillarÆs D10R dozers and Cat 994 front-end loader while Cat 854 wheel dozer has been fitted with CAESbasic. This investment in advanced machine guidance and control technology has proven very beneficial over the years for the Super Pit with improved safety and increased operating efficiency and productivity. The paper brings into focus how the CAES system adaptation in unique mining conditions assists in production gain, equipment operatorÆs safety, flexibility and independence, personnel removal from hazardous areas, acquisition of operational information and improvements in mine planning and design, benefiting the entire mining operation.

Jan 1, 2003

By M Hudyma

Open stope mining is the most common mining method employed in underground, hard rock mines in Canada. It is characterised by relatively small, single lift stopes (20 000 to 100 000 tonnes), and fast stope turnaround times. Host wall rock mass conditions, which are typically poor to fair, are the controlling parameter in stope dimensioning. Rock mass stability is maintained by designing all stope surfaces at a stable dimension, and through extensive use of cablebolting for stope backs and frequently stope hanging walls. Dilution control is a high priority. The typically small, high-grade, deep and irregularly shaped orebodies are incrementally developed, usually in a bottom to top direction. In many cases, high stress is encountered due to the depth of the orebodies. Overstressing of pillars and hanging pillars are avoided through the use of pillarless or early pillar recovery mine sequencing strategies. Stopes are invariably filled, and in higher grade and wider orebodies, cemented fill is commonly used. This paper generalises many of the similarities found in Canadian open stope mines.

Jan 1, 2000