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By Lama R. D

The Australian underground coal mining industry is undergoing major changes. This paper analyses the technologies presently being researched in mines, and discusses their utilisation as major contributors in the underground mining of coal in Australia over the next 20 years. It describes the problems that underground mining of the year 2000 will face and the possible solutions to those problems based upon results of present day research. Methods, equipment and organisational requirements are outlined. Developments in micro-electronics, computerisation and monitoring will require a new look into human resource development, education and training, and organisation to meet the challenges of the 21st century. The mining system's philosophies of the future are Outlined.

Jan 1, 1986

Industrial and telecommunications organizations around the world are now turning to optical fibres to satisfy their growing needs for data, voice and video communications and to solve transmission problems in noisy and hazardous environments. Already, coaxial cables have been made obsolete for intermediate and long distance applications and fibres are making in-roads on other copper cable and microwave system techniques.The idea of optical fibres is not new, but techniques to manufacture the high quality cable and components required have only recently been developed. Nonetheless, the technology is now advanced, reliable and mature, and costs are plummeting with increased production and market competition.The mining industry has benefited greatly from developments in electronics and communications over the years. Optical fibres are to have a further significant impact and the time is now right for the industry to begin to exploit the many advantages of this new medium. Applications include data transmission, long distance telecommunications, measurement and control systems, surveillance, computer networks, etc.This paper briefly describes the characteristics of optical fibres, current status of the technology, applications and possibilities for future development.

Jan 1, 1984

Japanese pig iron production in 1973 registered about 90 million tons. As clearly seen from the productivity (2.04 t/m3/D), and fuel ratio (494 kg/t-pig), the Japanese steel industry has maintained quite high levels of efficiency in blast-furnace (BF) operations. Among the many factors which have contributed toward these high levels of efficiency, the use of high quality coke is very important. The Japanese steel industry imports about 85% of its metallurgical coals from various countries of the world, including Australia. The effective use of these metallurgical coals of various origins in accordance with their re- spective properties is most essential for maintaining coke quality. This paper describes coking properties of various metallurgical coals and blending techniques based on these coking properties, in relation to the specifications of coke quality required for efficient BF operations. This paper also describes briefly new technology for expanding the scope of the use of coking coals.

Jan 1, 1975

One of the most difficult places to ventil ate in any mine is the working face area of an advancing mine heading. With an ever changing configuration, continual modification and extension to the ventilation system is necess- ary to maintain an adequate supply of fresh air and to control mixing and recirculation. Methane emissions and high dust levels as coal is broken and removed from the face area can produce unhealthy and dangerous conditions if ventilat- ion is not adequately monitored. An understanding of the air flow patterns which develop through use of different face ven- tilation systems can be reached by undertaking underground measurements or through observations using physical models. Tests undertaken by the author to determine the adequacy of different system-configurations are discussed together with approaches adopted by others working in the United States. Various new methods have been proposed for improving face ventilation beyond that sustained using conventional brattice curtain or tubing systems. The adequacy of some advances adopted by mining companies to improve ventilation while maintaining output efficiency is discussed.

Jan 1, 1983

Tourmaline-bearing rocks are a rare rock type of Suites 3, 4 and 5 at Broken Hill. Minor laminated plagioclase-quartz-tourmaline rocks occur in association with the quartz- magnetite rocks of Suite 3 with the greatest abundance of tourmaline-bearing rocks present in Suite 4 intimately associated with lode horizon, scheelite mineralisation and zinc mineralistion - all approximate strike equivalents of the Broken Hill Pb-Zn-Ag deposit. Bedded quartz-tourmaline rocks, tourmalinites, tourmaline-rich pelite and tourmaline-bearing lode horizon have been recorded from suite 4. The bedded tourmaline rocks rarely display cross bedding, graded bedding, slump structures and small scale intraformational breccias. Minor tourmaline-gahnite-bearing pelites are present in Suite 5. The sedimentary structures, metamorphic textures, the stratigraphic position of the tourmaline-rocks and the presence of quartz-tourmaline-gahnite-spessartine (-fluorapatite) lode rocks indicates that the mineralisation at Broken Hill and the tourmaline-rich rocks are all products of submarine exhalative hot spring systems which were most active during deposition of Suite 4 rocks. Tourmaline is chemically different from that associated with granitic activity and from other submarine exhalative tourmaline-rich rocks because the premetamorphic alteration at Broken Hill involved addition of Fe, Ti and F and subtraction of Mg - a feature reflected in the chemistry of tourmaline from Broken Hill.

Jan 1, 1983

The Hunter Fracture Zone can be traced into the Fiji group, and onshore SE Viti Levu in the form of NE-trending morphostructures. NW- trending morphostructures offset the NE elements. Structural mapping of Suva Harbour indicates that the NE elements are grabens bordered by faulted monoclines. Faulting is characterised by block-rotations and dip-slip displacements. The NW morphostructures are faults displaying elements of both dip-slip and strike-slip movement. Structural overprinting suggests that the NW faults represent the youngest phase of deformation, and current seismic activity occurs on this trend. A conceptual, geomechanical model of the deformation invokes toppling and wedge failure at the edge of the Fiji platform, translating material downslope into the Hunter Fracture Zone. The interference pattern produced by the superposition of the NW on the NE structures consists of a series of circular features bearing superficial resemblance to volcanic centres. Known mineral deposits in SE Viti Levu correspond closely to these features. The formation of the circular features postdates mineral genesis, suggesting that the features provide a focus for the enhanced exposure of mineral deposits rather than a source of mineralisation. There is a close association between mineralised exposures and interference patterns in extensional structures in SE Viti Levu, and a correlation between these structures onshore, and the Hunter Fracture Zone cum South New Hebrides Trench offshore. Future mineral exploration in the SW Pacific will benefit by closer consideration of the geologic structure of Pacific islands bordering the extensional regimes of deep oceanic trenches.

Jan 1, 1987

An empirical method of estimating dense rock (D.R.E.) equivalent volumes erupted as airfall tephra, described in a companion paper in this volume, is elaborated, and its accuracy discussed. Estimates obtained from a single eruption can be classified as to whether they show positive, negative, or constant relative dispersion. For positively dispersed tephras (estimated volumes increasing with distance), this procedure improves the accuracy of the method. The technique is applied to selected andesitic tephras erupted from Egmont Volcano, New Zealand, during the last 28 000 years, which are found to range in volume from about 1.5 x 107 m3 up to about 2.4 x 108 m3 D.R.E. With a factor of about 16 between the smallest and largest volumes, this contrasts sharply with the rhyolite volcanoes in New Zealand, where the difference factor is usually of the order of 100. The largest tephra eruptions at Egmont are small compared to the largest debris avalanches, which have exceeded 1010 m3 (10 km3) in volume.The magnitude versus frequency relationship, calculated using a maximum likelihood method, establishes the limits of eruption magnitude at Mt Egmont as 107 to 109 m3 D.R.E. For some volcanoes, the magnitude-frequency relationship changes with time, owing to clustering of eruptions, separated by long dormant intervals. Ngauruhoe Volcano, New Zealand, is an example. Within eruptive episodes, the mean interval between eruptions of >_ 105 m3 is about 0.9 ¦ 0.65 years. The mean interval between eruptive episodes in which >_ 106 m3 is erupted, including episodes in which this volume is erupted gradually, is about 25.8 ¦ 6.6 years, and the mean dormant interval between all episodes is about 5.2 ¦ 3.0 years. At present Ngauruhoe is in an unusually prolonged dormant period, 50% longer than any in the historical record, since 1839.

Jan 1, 1990

By Lewis PC, Carr GR, Dean JA, Glen RA

The Lachlan Fold Belt (LFB) is a complex orogenic belt which developed in Early to Mid Palaeozoic time. A number of orogenies and more localised deformational events affected the region. A simplified classification scheme for the diverse gold deposit types is proposed, subdividing primary mineralizing processes into four categories: volcanism (epithermal and volcanogenic deposits), igneous intrusion (subvolcanic/porphyry style, skarn and magmatic deposits), metahydrothermal processes (deposits generated during metamorphism and regional deformation) and hydrothermal-distal processes (deposits generated by poorly understood, generally remote large scale hydrothermal processes). Major gold deposit associations include epithermal and porphyry style deposits in Ordovician-Early Silurian shoshonitic andesite sequences; volcanogenic base metal-gold deposits in Silurian rift or basin felsic sequences; vein deposits in Late Silurian and Early Devonian S and I-type granitoids; deposits in Early Devonian sedimentary rocks of the Cobar Basin probably generated by metahydrothermal processes during basin closure and cleavage formation; deposits associated with serpentinite; and metahydrothermal quartz vein deposits in folded sedimentary rocks.Studies of host rock geochemistry suggest a relationship between magma types, gold enrichment and mineralization particularly in shoshonitic sequences and Early Devonian granitoids of the Boggy Plain Supersuite. Structural studies indicate the importance of thrust type structures and detachment faults in generation and location of gold mineralization. Lead isotope initial ratios help define metallogenic associations and a number of distinctive isotope "signatures" have been established.

Jan 1, 1990

Newmont Australia Limited has for some 15 years mined a number of large open cuts associated with the Telfer Gold Dome deposits. The principal ore body exploited has been the East Flank of the Main Dome where a very high grade gold reef deposit of mixed metal sulphides, grades in excess of 20gA Au, has been mined in conjunction with dissemi- nated mineralisation contained in the overburden material. The main ore body has been under review for some years as an under- ground mine, however due to the ore body widths of less than 1 metre and a dip generally less than 35 degrees and a very weak host rocks earlier studies all resulted in a continuation of open pit mining activities. In early 1988 it was recognised that open cast mining would not be able to mine all of this valuable resource and a feasibility study was commenced to come up with a practical and economic approach to underground mining.

Jan 1, 1991

By L E. Krause

This paper discusses the considerations for optimum maintenance of critical ore handling infrastructure in order to minimise the cost to the business of maintenance periods. As maintenance periods are a direct interruption to production, time is of the essence and careful management of shutdown periods is essential. The ore pass systems currently in use at Xstrata Copper û Mount Isa Copper Operations are up to 30 years old and have had significant wear over the years. The maintenance of these passes and their brows and chutes in a production situation is a challenge as it can potentially expose personnel to high risk situations in addition to the production interruptions. Some alternatives for mitigating the risk of working in ore passes including plugging and ballooning are described. Criteria are included for selecting a method for the safe entry into a given ore pass. Experience in adapting the method of ore pass plugs and some lessons learnt in the process are also discussed.

Jan 1, 2005

By Brett J. R

Some recent and current research and development projects relating to strip type open cut coal mining are reviewed. The projects include a dragline-hopper-truck mining system, an overburden slusher system, improvement of dragline operations, continuous excavation and conveying of overburden materials, and a steep angle coal conveying system. Most of these projects offer prospects for reducing costs in deep strip mining operations, but only the overburden slusher project has the potential for large cost reductions. A project on highwall mining of coal has demonstrated that this coal mining system is viable and capable of achieving high productivity rates. Production highwall mining operations are now starting to become established in Australia.

Jan 1, 1991

By Storey AG

Following initial plant scale work on the development and performance of 'spray' oil lances, a full scale room temperature model of the blowpipe-tuyere region of a blast furnace was built to study the basic aerodynamic features of auxiliary fuel injection procedures. Mobilwax 2305 was used as a substitute for Bunker C oil fuel in view of its similar physical properties and the fact that the atomised droplets could be frozen in flight and size, distribution analyses made for various operating procedures. It was shown that secondary atomisation processes far outweighed the importance of any primary atomisation procedures in determining mean Sauter Diameters particularly at high windrates typical of current blast furnace technology. It was also found that good spray dispersions across the blow pipe could only be obtaind for liquid fuels and that the lateral rate of spray dispersion was substantially enhanced by primary atomisation procedures. Mean particle diameters of sprays were found to be predictable on the basis of elementary stability theory and fell within the size range necessary for good combustion at all liquid fuel rates studied. The possible effects of high oil injection rates on flooding phenomena in the furnace bosh were considered. Comparisons show that high oil rates can lead to significant increases in the hanging factor (e.g. 'V 10% at 135 kg oil/thm) owing to increased gas flow rates/thm resulting from the presence of hydrogen.

Jan 1, 1975

The relative contents of Au in a series of groundwaters from water bores and exploration drillholes, located near Au mineralisation at Stawell, Ararat, Clunes and Ballarat in central Victoria, were found to be clear indicators of relative proximity to mineralisation in each region. In the same series, waters with anomalous concentrations of As distinguished Au mineralisation in bedrock from secondary palaeochannel or deep lead Au. In some groundwaters, acid pH values, high sulphate relative to other anions and detectable concentrations of reduced Fe reflected sulphide minerals associated with bedrock Au deposits. Close to some ore zones, locally anomalous groundwater concentrations of Mn reflected the Fe carbonates that accompany Au in these zones. In addition, elevated concentrations of other elements provided geochemical signatures for the aquifer lithologies associated with Au mineralisation. Of the lithological indicators Co and Ni, U and F, Rb and Cs, Mo and Li respectively reflected the mafic, felsic, potassic rich and quartz zones, principally in the Stawell mine area and to a lesser extent those at Clunes and Ballarat. Mineral stability diagrams, based on groundwater activities of K', Mgt and H`, demonstrated that a series of ore-zone groundwaters follow a trend that conforms with a biotite to sericite to kaolinite alteration sequence in aquifer mineralogy. This is a good illustration of how present day groundwaters under surface conditions can reflect the underlying mineral sequences that accompany these Au deposits. These observations around mine areas suggested that groundwater chemistry could provide a rapid and cost effective method of assessing prospectivity for An of extensive areas in central Victoria. To test this, regional sampling and analysis of 355 bore waters was carried out in a region where potential An bearing rocks are covered by Mesozoic and Cainozoic sediments and volcanics. Contoured elemental abundances and distribution from this program indicated five zones in which groundwaters had elevated Au and despite the cover, appeared to reflect variations in the underlying Palaeozoic rocks. Three of the Au zones could be in terrain affected by extensions or intersections of faults, a feature in common with the established Au deposits in central Victoria. Reflections of concealed Palaeozoic rocks included a possible zone of concealed Cambrian greenstones that coincides with three of the Au zones. It was concluded that each of the An zones represents a groundwater Au focus that warrants follow-up exploration.

Jan 1, 1997

By K Peters, C McKenzie

New Zealand has an established history of gold production beginning with the gold rushes of the 19th century in the Coromandel, Nelson/Marlborough, West Coast and Otago regions. Despite this, the number of significant modern hard rock gold operations has been limited in recent years due to a lack of sustained exploration capital and not limited geological prospectivity.The New Zealand Government is actively encouraging explorers to invest in New Zealand through a series of targeted promotional visits, more importantly through the acquisition of precompetitive regional geophysical data. Data collection has been completed over the prospective Northland epithermal district and a large portion of the South IslandÆs west coast that is prospective for both orogenic gold and intrusive related gold.Analysis of new data has been an important component in aiding the generation of exploration targets from prospectivity modelling. Determining the prospectivity of an area involves reviewing all the available data and analysing it with respect to the most up-to-date mineral system model for the mineralisation style of interest. Using the weights of evidence modelling approach, the most prospective areas for epithermal gold-silver, orogenic gold and intrusion-related gold have been identified. The key exploration parameters relevant to each mineral system are first represented spatially and then statistically combined into a single prospectivity map. New potentially economic deposits could be found by focusing exploration on targets identified from these models. The prospectivity modelling approach can greatly reduce the risk involved in mineral exploration.CITATION:Peters, K and McKenzie, C, 2013. New Zealand gold potential - using mineral prospectivity modelling to evaluate gold-bearing mineral systems in an underexplored country, in Proceedings World Gold 2013 , pp 479-486 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 26, 2013

Ore deposit modelling is becoming an increasingly accepted tool in mineral exploration. Successful models have already been proposed for several ore deposits of base metals and gold, but tin has so far received comparatively little attention, perhaps because of an excessive preoccupatioi with alluvial operations. This situation is rapidly changing and some of the world's most profitable and newly commissioned tin mines are large, primary tin deposits. Some basic principles of ore deposit modelling are briefly reviewed and the fallacy of an excessive reliance on grade tonnage diagrams based on the tin industry worldwide is discussed. The four proposed models and submodels of large, hard-rock, tin deposits focus on basic concepts such as the spatial relationship with "tin granites", depth of emplacement and the level of erosion. General concepts are drawn. The modelling of large primary tin deposits is reviewed not only in its geological and exploration aspects but also in its mining and economic implications.

Jan 1, 1986

By Schneider CL

The calculation of the liberation spectrum in the product from continuous milling operations is a problem of considerable importance, and it is difficult to solve because the population balance equation must be integrated in two-dimensional space. Complete solutions require a very detailed knowledge of the complex interactions between the fracture patterns and the mineralogical ore texture when brittle particles are subject to impact fracture. Most of the liberation models that have been developed to date apply only to batch comminution processes and under these conditions the liberation problem can be studied in isolation. When the comminution is continuous and forms a unit operation in a flowsheet that includes classification and separation operations, the situation is very different, and then the liberation of the minerals must be described when single particles of known mineralogical composition are fractured. Important industrial examples are conventional milling circuits closed by hydrocyclone and regrind mills in flotation plants. This paper presents an efficient computational algorithm for the calculation of the liberation spectrum produced by continuous milling operations. The algorithm relies heavily on the detailed internal structure of the Andrews-Mika diagram. The modifications that are required to make this diagram apply to practical ore minerals, and the internal structure of this diagram can be established using single-particle fracture on mono-size, mono-grade material but suitable liberation models are essential to interpret the data in terms of the cross transfer coefficients required for the population balance procedure. Models proposed by Leroux (1992) and King (1990) are compared to experimental data.

Jan 1, 1993

By Jamsa-Jouneia SL, Lahteenmaki S

Sophisticated control systems require sufficient and reliable information from the process to be controlled. At the Pyhasalmi concentrator two novel measurements, a particle size indicator (PSI) and a mill level monitor (MLM), have led to significant progress in the control of the grinding circuit. The PSI and the MLM measurements have brought additional information from the process. The PSI has been an absolute prerequisite for determining the overall grinding circuit efficiency and the design of the integrated grinding and flotation control system. The MLM measurement has enabled studies on the volumetric filling of a mill to be utilised for maximising the mill throughput. The paper describes the operation principles of the PSI and MLM devices and the additional process information received. The results of a metallurgical pre-control audit are discussed and finally the design of the integrated control system is outlined.

Jan 1, 1993

The structural pattern of Victoria shows the presence of EW, NW, NE as well as the more readily recognised NNW factors commonly associated with the goldfields. ENE and WNW trends are also present. This structural lattice affects all rocks of the State. Landsat imagery shows that the EW, NW and NE structural elements are closely related spatially to the distribution of Palaeozoic igneous intrusives, Cainozoic volcanic vents as well as all historically important gold mines. It is suggested that the EW, NW and NE structural grid visible on landsat imagery is a reflection of the structure of a mid-crustal layer situated between 3.5 and 17 kms below the surface. The points of intersection of the structural elements of the mid-crustal layer offer most favourable loci for the escape of energy in the form of heat. The correlation between the distribution of igneous plutons, volcanic vents and centres of mineralisation, all reliant on high levels of energy for their formation, indicates the stability of the structures of the mid-crustal layer since early Palaeozoic times. The deep level crustal structures are believed to be, related to the release of stresses placed on the crust since early Palaeozoic times by the rotation of the Earth. A geological model that accommodates the presence of a mid-crustal layer as well as the complexities of the recognised orogenic cycles of southeast Australia is suggested. All 1 000 kg Au reef and deep lead mines fall within 1.5 and 2.5 km respectively of strong linears associated intimately with plutons and volcanic vents. Future exploration of the State is more likely to meet with success if it too is confined to the evaluation of these and similar linears. The mode of mineralisation of any one centre will depend upon the temperature, pressure and geochemical gradients operating on the migrating mineralising fluids as well as the structures in the host rocks. These factors are likely to have varied considerably from one centre of mineralisation to the next and consistency of mineral isation form and depth should not be expected along the length of any single Linear.

Jan 1, 1986

By Jankowski P

The Bannockburn gold deposit is located 67 km north-west of Leonora in a poorly exposed part of the Norseman-Wiluna belt of Western Australia. The deposit consists of narrow, complexly shaped orebodies which have presented a challenge to find successful grade control and mining methods. The deposit also presents an opportunity to examine in detail the geology of this part of the Norseman-Wiluna belt.This paper discusses the geology and structure of the Bannockburn gold deposit as well as the grade control and mining systems developed to define the ore and extract it with minimum dilution. We discuss the different techniques employed for grade control in the past and their shortcomings, and the evolution of the present system of doing grade control in cross section from blast hole assays.

Jan 1, 1993

By Seymour K. M, Sampson D. B, Walker I. W

Ashton Mining Limited is the operator of two wholly-owned gold mine/mill complexes at Laverton and Leonora. In addition, Ashton owns 43% of the Bardoc Joint Venture mine/mill complex, which is operated by Aberfoyle Pty Limited. All three of these operations are located in the Eastern Goldfields region of Western Australia (Figure 1). At Laverton, milling capacity is in the order of 1 million tonnes per year in 3 mills (Duketon 200,000 tpa, Cork Tree Well 650,000 tpa and Craiggiemore 150,000 tpa). These mills service a distance of 80 km, from Baneygo in the north to Craiggiemore in the south. Mineral tenements cover a 150 km long stretch of a series of sub-parallel mineralised structures. At Leonora, the Harbour Lights mill is designed to treat 750,000 tpa of sulphide ore, and has treated oxide ores at an annualised rate of over 1 million tonnes/year. The mill is supported by several tenement blocks that lie within a 50 km trucking radius of the mill. The most important of these is the Mertondale tenement block, which covers approximately 25km of the Mertondale Shear Zone.

Jan 1, 1991