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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

By Drew GJ

Smelting is a process in which heat is applied to ores to produce metals. Impurities are removed by segregation in the slag, or converted to gases or sublimates and discharged up the flues. Mate- rials delivered into the smelter have generally been previously concentrated or processed at the mine, and the size of their particles, and also their chem- ical composition, greatly affect the smelting proc- ess. Some impurities are more difficult to remove than others, and are more objectionable in the finished product. The first metal mine in Australia was opened near Glen Osmond in South Australia in 1841, for silver-lead ore. It was followed by the Kapunda Mine for copper in 1844 and by the very signifi- cant Burra Mine, also for copper, in 1845 (Figure 1). A major part of their ores could not be exported profitably for smelting in England and Wales where the large smelters were then located. In addition to treating ores from Cornwall these also smelted ores from recently opened mines in Cuba, Chile, and Mexico. The Welsh smelting process (Figure 2) was developed over a period of years to utilise Welsh coal to treat copper ores particularly from Corn- wall. The first step consisted of a calcination to remove sufficient sulphur from sulphide ores so that subsequent melting operations would produce copper matte, a copper-iron-sulphide which melted at about 1050¦C. Subsequently refined to white metal with the addition of carbonate and oxide ores when these were available, and often through an intermediate step of blue metal, this matte was finally oxidised to pure copper, or as pure as it could be made in those days. The movement of metal towards greater purity was matched by a reverse flow of slag, carrying reducing quantities of copper, so that the slag rejected from the first melting process carried the minimum quantity of copper. Chemical analysis was virtually unknown. Materials were assayed in the laboratory by a small scale smelting process, and the purity of the final refined copper was judged b} the ease with Mhich it could be hammered into thin sheets.

Jan 1, 1987

By T Leach, F Kaiqiang

The Jianchaling gold deposit is located about 1200 km south west of Beijing in central China. The deposit was discovered in 1988 by the Northwestern Geological Exploration Bureau (711 Exploration Team). Sino Gold Limited, an Australian based company, developed the mine in 1998 and is currently operating a 1000 t per day underground mine, producing about 80 000 ounces of gold per year. The pre-mine resource for Jianchaling was 1.6 million tonnes at 9.85 g/t gold. The deposit occurs within the east-west trending Mesozoic Qinling-Dabie orogenic belt formed during the Yanshanian Orogeny. In the Jianchaling region, gold mineralisation is primarily hosted by regional west-northwest to east-southeast striking faults, the most important of which, the reverse sinistral F145 fault, hosts the larger gold deposits including Jianchaling. At the mine scale, the most important zone of mineralisation is localised within a shallowly north dipping dilation on the F145 fault. Proterozoic dolomite forms the hangingwall and serpentinite and talc schist the footwall to the fault. Within the footwall, serpentinite is the most important host rock to mineralisation. Initial alteration involves replacement of serpentine to dolomite ¦ pyrite, talc to ankerite ¦ pyrite, and magnetite and chromite to pyrite, the latter locally through a transitional hematite phase. Proximal to feeder structures, the carbonate minerals have undergone partial dissolution and replacement to quartz. Gold is related to arsenean pyrite and marcasite rimming and replacement of early-formed pyrite, and associated with iron release during the processes of dolomitisation, silicification and carbonate dissolution.

Jan 1, 2004

By Nemick JA

Recent advances in computer simulation together with field measurements of caving and microseismic activity about longwall panels, has allowed a much better understanding of the caving process and the variability due to geology. The joint research between SCT Operations and CSIRO Division of Exploration and Mining has initiated new methods of computational modelling predicting various caving patterns and strata failure far ahead of the longwall face. This work was validated by field measurements of caving and microseismic activity at the longwall face.The rock fracture distribution and the caving characteristics of a range of strata sections have been simulated by computer methods. Validation studies of the method were addressed together with case studies. The interaction of caving with support convergence and face control is presented. The method allows the simulation of longwall support behaviour under various geological conditions. The system also allows a prediction of the monitoring data, which is best suited to give an early warning of weighting events or signal various key caving characteristics.

Jan 1, 1998

By Paine GG

The Kidston Gold Mine commenced mining in 1984 and current annual production is 12 million tonnes, increasing in 1990 to 18 million tonnes. Mill throughout per year is 4 million tonnes with the balance of material being waste. The operation is a conventional hard rock open pit truck and shovel operation mining 12 metre benches. Buffer blasting is utilized to minimize post blast movement of the broken rock to maintain grade control.

Jan 1, 1988

By I Jabouri

There are many physical factors that can affect the self-heating rate of coal. The presence of seam gas has often been referred to as inhibiting coal self-heating due to the limited access of oxidation sites created by the presence of the gas adsorbed on the coal pores. Similarly, the presence of bed moisture in the coal also acts as an inhibitor of oxidation by blocking access of air into the pores. Gas drainage of a coal seam prior to mining removes both gas and moisture from the seam. Bulk coal self-heating tests in a two-metre column on both gassy, as-mined and gas-drained, dried high volatile bituminous coal show that removal of gas and moisture from the coal accelerates the rate of self-heating to thermal runaway from 8.5 days to 4.25 days, from a start temperature of 30¦C, with an airflow of 0.25 L/min. The corresponding gas evolution pattern for each of these situations is different. Therefore, it is necessary to take this change in coal condition into consideration when developing a spontaneous combustion management plan.

Jan 1, 2005

The BLEG (Bulk Leach Extractable Gold) technique is a semiquantitative measure of cyanide extractable gold contained in a sample. A 5kg sample is leached in cyanide solution for 24 hours and gold is precipitated out of the pregnant solution using zinc and assayed by AAS. The detection limit is reported as ppb (parts per billion). Telfer is located 1300km north north-east from Perth in the Great Sandy Desert. The climate is one of hot summers with irregular rainfall and mild winters. A large portion of the area is covered by aeolian sand and seif dunes with poorly developed drainage, rare outcrop; topographic relief is a maximum of 96m. Poor outcrop and poorly developed drainage render conventional stream sediment sampling and soil geochemistry inadequate. Therefore a technique providing a minimum number of samples with maximum accuracy and sensitivity was needed. Consequently BLEG orientation surveys were conducted over the Telfer Mine area in 1983, 1984 and 1985.

Jan 1, 1988

By F Soleimani

Coal and gas outburst is a common hazard in coalmines and due to the complexity of its nature, efficaciously predicting the possibility of its occurrence is intricate. The mechanical and gas flow properties of coal, in situ and mining-induced stresses and geological structure are involved in outburst occurrence, whereas suggested thresholds for its prediction do not consider them all. Numerical modelling is known as an effective method that can not only consider couple the effect of different physics but also analyse the effect of associated parameters. In this paper, a coupled fluid flow and geomechanics model has been developed in COMSOL Multiphysics to simulate outbursts by considering the effect of gas pressure and composition, damage mechanics on related coal properties, and progressive excavation and mining-induced stress. For the proposed fully coupled outburst model, the effect of pore pressure and sorption are applied to the stress while the influence of stress changes and damage are considered in updating coal porosity and permeability in each time step. In addition, to study the effect of mining-induced stress, the excavation process is simulated by changing the material properties over time according to the schedule of heading development. Then, outburst initiation is analysed from the energy point of view by using the concept of energy conservation law. The simulation results are used in calculating energy sources of the outburst initiation, also, the effect of particle size and ejection velocity are studied, and the significance of particle size effect on the energy analysis and deformed coal on outburst initiation is discussed.

Oct 12, 2022

By I Zulkarnain, H Permana, R A. Binns

Through an ambitious but relatively low-cost program of marine fieldwork, laboratory investigations and technology-transfer and training activities, three Indonesia-Australia-led marine expeditions were undertaken aboard KR Baruna Jaya VIII between 2001 and 2003. These IASSHA (Indonesia-Australia Survey for Submarine Hydrothermal Activity) cruises have sought to discover and investigate a variety of potential ore forming hydrothermal systems in a range of tectonic settings. All cruises have been successful, both scientifically and from the point of view of training, creation of capabilities and capacity building for such research in Indonesia. Over 60 scientists and technicians from Indonesian and Australian institutions and agencies have been involved. Three new sites and a possible fourth site of hydrothermal activity were discovered in the Sangihe arc in northern Sulawesi. Surveys in the Tomini basin tested a hypothesis based on previous data which suggested this might be an isolated anoxic, brine-filled basin over 2000 m deep where igneous heat sources existed to generate hydrothermal mineralisation. The bay, however, was found to be open to adjacent deep ocean circulation, and there was no evidence of massive base metal sulfides. Subdued evidence of hydrothermal activity was found in the Sunda Strait associated with the famous Krakatau volcano and the extension of the seismically active Semangko Fault. The BANDAMIN program (Indonesia-Germany) covered a portion of the Banda arc in eastern Indonesia, and also found evidence of recent hydrothermal activity and epithermal sulfide mineralisation.

Jan 1, 2004

By Bourke J. H, Ashcroft T. B

Many changes have occurred in the world market for manganese over the last five years. Among these, the emergence of divided steel processes for the hot metal refining of pig iron is affecting the use of both ferruginous manganese ore and ferro manganese, at this stage particularly in the Japanese steel industry. Subsequent demand for higher quality manganese materials is promoting the use of thermally beneficiated products such as sinter. In addition, many processes are being developed for the direct smelting of fine manganese ores, of which plasma technology is the most advanced. Cost pressures and product quality requirements are encouraging pre- viously self sufficient countries such as The People's Republic of China and the USSR to import high grade manganese ores to supplement indigenous lower quality supplies. At the same time, Brazil has been provided with the impetus to convert its substantial reserves of ore to value added products.

Jan 1, 1988

By N Collins, A Woodley, A N. Danoucaras, C McCombe, N C. Kunz

Over the past decade, the mining industry has come to recognise the importance of water both to itself and to others. Water accounting is a formalisation of this importance that quantifies and communicates how water is used by individual sites and the industry as a whole. While there are a number of different accounting frameworks that could be used within the industry, the Minerals Council of AustraliaÆs (MCA) water accounting framework (WAF) is an industry-led approach that provides a consistent representation of mine site water interactions regardless of their operational, social or environmental context that allows for valid comparisons between sites and companies.The WAF contains definitions of off-site water sources and destinations and on-site water use, a methodology for applying the definitions, and a set of metrics to measure site performance. The WAF is comprised of two models: the input-output model, which represents the interactions between sites and their surrounding community, and the operational model, which represents on-site water interactions.Members of the MCA have recently adopted the WAFÆs input-output model to report on their external water interactions in their Australian operations, with some adopting it on a global basis. To support this adoption, there is a need for companies to better understand how to implement the WAF in their own operations. Developing a water account is non-trivial, particularly for sites unfamiliar with the WAF or for sites with the need to represent unusual features. This work describes how to build a water account for a given site using the input-output model, with an emphasis on how to represent challenging situations.CITATION:Woodley, A, Danoucaras, A N, McCombe, C, Kunz, N C and Collins, N, 2013. A robust methodological approach for mine site water accounting, in Proceedings Water in Mining 2013 , pp 335-342 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 26, 2013

By Bratt G. C, Horsham T. R, Langlois D. R

Mercury is precipitated from weakly acidic sulphuric acid plant waste liquor at the Risdon Works of the Electrolytic Zinc Company of Australasia Limited. Factors determining the choice of process and reagent, as well as details of process development including scale- up, and the time scale of implementation are outlined. The plant is designed for a maximum flow of 120 m3/h.of liquor containing mercury and saturated with sulphur dioxide. Mercury is precipitated by fluidised beds of aluminium pellets contained in lead columns. Liquor is then clarified with plate and frame presses. Experimental work on the mercury precip- itation reaction was conducted in three phases involving a scale-up of 100 times in equipment size. Extensive pilot filtration work was carried out on a 1 m2 press. Scale-up of 120 times was required for specification of plant filters. The basis of scale-up is outlined.

Jan 1, 1977

The Electrolytic Refining and Smelting Company of Australia Limited (ER&S) operates a copper smelting and refining plant and is situated close to the heart of the highly industrialised area of Port Kembla. In March, 1982 the Company entered into an undertaking with the State Pollution Control Commission (SPCC) to monitor ambient levels of sulphur dioxide (S02) gases present in the atmosphere in the surrounding urban area. Despite the use of a 200 metre high stack for dispersal of the smelter waste gas stream at ER&S, two local suburbs, Warrawong and Primbee were experiencing on occasions high ambient concentrations of S02 resulting in discomfort to local residents. In late March 1982, ER&S installed a highly advanced S02 monitoring system to continuously monitor the levels at Warrawong. The system was extended to include S02 monitoring at Primbee in November 1982, and further extended in June 1983, to include an input of meteorological data. Initially the system was designed to monitor and react to high concentrations of S02 at either of the two monitoring stations. Currently however, refinement is taking place to allow a predictive nature to be built into the system such that it not only reacts to an adverse situation but can predict weather patterns likely to cause high concentrations and thus avoid these events. The entire system is still undergoing a growth and development period, however the results obtained to date are pleasing to both the Company and the SPCC.

Jan 1, 1984

From the viewpoint of mechanical efficiency, charges should be fully coupled and, upon detonation, should just fail to break the rock in compression. But because mining thrives on its cost-effectiveness rather than its mechan- ical efficiency, the explosive which generates maximum energy per $ should generally be used, even though the mechanical efficiency of this explosive's detonation products may be sub- optimum. Wherever possible, each charge should have a length:diameter ratio of about 20 or more and should shoot to a concavely biplanar free face that is both parallel and reasonably close to the blasthole. Success in obtaining parallel effective faces often demands the drilling of angled blastholes and, hence, will require intensified research and development efforts by drilling manufacturers, especially where hard strong rocks are encountered. Blastholes should be drilled on equilateral triangular grids and fired in a Vl or shallower V-type sequence using inter-row delays which ensure that good pro- gressive relief of burden is achieved. The conventional method of calculating Se/Be values (on the basis of planar effective faces) is often invalid.

Jan 1, 1986

The Mine Safety and Inspection Act, 1994 of Western Australia recognises the importance of ground control in underground mining. The recent safety performance of underground mining is summarised in terms of the most common causes of injury and fatal accidents. A review of current ground control practices is presented and the concepts of local and large-scale ground control are introduced. The need for a more systematic approach to ground control is considered to be directly related to requirement to improve safety performance. The new regulations will require that certain geotechnical issues be addressed during the life of a mine. To comply with the regulations it is suggested that a ground control management plan be developed for each mine. The geotechnical issues associated with the ground control management plan are reviewed and hazard recognition aspects discussed.

Jan 1, 1995

By Feebrey CA, Duncan RA

The Ebor Volcano in northeastern New South Wales is an eroded example of a central-type intraplate volcanic-intrusive complex. It is of Miocene age (19-20 Ma) and has similarities to other central-type volcanoes in eastern Australia which may represent manifestations of sub-lithospheric hotspot activity. Thick lava flows are exposed around the Great Escarpment and are dominated by a tholeiitic basaltic suite, ranging from ol-tholeiite to qz-tholeiite to icelandite with ages of 19.2-19.6 Ma. On its western edge, the tholeiitic lava suite probably overlies remnants of basanite flows belonging to the Eocene (-48 Ma) Doughboy province, but elsewhere, minor alkaline basaltic lavas may be coeval with the tholeiitic suite. Several felsic bodies were emplaced into the volcano at -19.0-19.2 Ma and include subalkaline and peralkaline types. The Crescent Complex is a Miocene-age, strongly differentiated mafic to felsic intrusion in basement rocks and centrally located in pre-erosion reconstructions of the Ebor Volcano. It is interpreted to be a major feeder for the tholeiitic lavas based on age and composition. Evolution of the dominant tholeiitic suite proceeded from a parental ol-tholeiite magma, through qz-tholeiite, icelandite and small volumes of felsic rocks by fractionation of plagioclase, olivine, clinopyroxene and titanomagnetite, accompanied by enrichment of SiO2, F,FeO/MgO, alkalies and HFSE.

Jan 1, 1995

The excavation of a tunnel through rock and mixed ground of basalt and silty clays presents a challenge to engineering organisations. Such was the situation facing the Melbourne and Metropolitan Board of Works (MMBW) in constructing the 15.3 km, 5.5m dia. tunnel component of the new Western Trunk Sewerage System. The tunnel geology showed that there were two distinct components to the excavation - rock and mixed ground. By drawing on extensive experience in the use of Tunnel Boring Machines (TBM's) used previously by the MMBW and using techniques developed for predicting TBM per- formance, a comparison of the options of drill and blast versus TBM was made. The conclusion was that TBM methods would provide the best solution to the problem. Tenders were called for the supply of a TBM. A performance specification was used to attract tenders offering designs which re- flected the state of the art on an internation- al level. Particular features required by the MMBW were included in the specification. The excavation planning and operation are described in this paper. The production achieved has shown that the TBM can very adequately handle rock excavation (best weekly production 167.9m). Extreme conditions of mixed ground with heavy groundwater inflows have been handled using an auxiliary thrust system to maintain gripper reaction through the soft ground encountered.

Jan 1, 1987

By Cleghorn JH

Underground mining operations on Kalgoorlie's Golden Mile were suspended in 1976, suffering the combined effects of low gold prices and grades. A subsequent substantial increase in the gold price led to the decision by Kalgoorlie Mining Associates to reopen their mines in 1979. The two shafts selected for access required excessive maintenance. The geological assessment and development parameters prescribed have been successfully used to establish reserves to maintain production at a 390 000 tonnes per annum rate. While ore reserve grade is being maintained from primary stoping sources, supplementary lower grade ore is drawn from remnant pillars and stopes at lower cost.Performance by the workforce has reached levels previously attained and a record tonnage was hoisted in the fourth year after recommencement.Keywords : Golden Mile lodes, geological research, payruns, cut and fill, mill holes, gold price, ore grade, amalgamation.

Jan 1, 1984

By Rosengren KJ

Geotechnical conditions often have a critical influence on the design of new open pit and underground mines, but they are often considered of secondary importance in relation to other factors, such as detailed geology, orebody geometry and grade distribution. As a result, geotechnical studies may not be carried out during early project investigations or, at best, may be given only superficial attention, often to the overall detriment of the project. Technically and economically, it is logical that geotechnical studies should be integrated with geological investigations as soon as it becomes evident that the particular deposit may prove to be economic. The paper discusses the use of geotechnical information in the selection of mining methods and mine design for underground mines and for wall design and assessment of excavation characteristics in open pit mines. It then considers methods of obtaining the relevant data, with particular reference to exploration boreholes. Selected case studies on the application of geotechnical data to mine design are Included.

Jan 1, 1986

By Artmont G. J, Palmer K

Alluvial gold is an ideal exploration tracer to bedrock source and indicator of bedrock mineralisation style because (i) gold occurs in a wide range of deposit types, (ii) primary composition is sensitive to style of mineralisation, and (iii) it is a heavy resistate mineral that is readily preserved and easily sampled. In regional exploration of the Central Ranges of Irian Jaya, alluvial gold mineralogy has been applied to maximise the information return from panned concentrate sampling and to focus exploration effort. Primary gold is a solid solution of Au+Ag¦Cu¦Hg, ¦ trace Pd, Te, and Sb. In general Ag¦Hg increase and Cu decreases with inferred decreasing temperature of formation, and gold from particular mineralisation styles has signature compositions that can be used as indicators of bedrock mineralisation type. Furthermore, the abundance of alluvial gold is an indicator of the economic potential of a catchment. The convergent continental-oceanic plate geology of the Central Ranges is conducive to a wide range of mineralisation styles. Mineralogy of gold in ophiolite, skarn, porphyry, mesothermal vein and possible VHMS environments is characterised from alluvial and bedrock samples, and the use of gold mineralogy in prospecting at regional scale through prospect definition to drilling is demonstrated.

Jan 1, 1995