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By Wilson R. G

Mining conditions imposed by a coal seam roof can be analysed according to natural causes, before consideration of strata control. All types of roof behaviour can be explained by considering only three independent variables. They are roof rock types, rock stresses and discontinuities. Roof rock types encountered in the Sc.ithern Coalfield of New South Wales (NSW) are sandstone, shale, mudstone, laminite and coal. Each rock has its own mode of failure. Lithological stability of the sediments varies from one type to another. Regional stresses upon a coal seam roof will vary in magnitude according to the proportion of gravitational stress, which is related to depth of cover, and residual stress, which is related to the maximum depth of burial and may be gauged by coal rank. Local stresses will vary according to tectonic deformation, related to irregularities in seam structure.

Jan 1, 1976

By Waters JC

Pseudoclastic hydrothermal alteration textures occur within quenched coherent dykes forming part of a subaqueous dome complex (-4 Ma) on Ponza Island, Italy. These textures are similar to those observed in considerably older (-500 Ma) subaqueous volcanic rocks at a number of localities throughout the Mount Read Volcanics in Tasmania and elsewhere in ancient volcanic sequences of this type in Australia. This is significant because the processes of formation, hydrothermal alteration and secondary mineralisation of ancient volcanic sequences may be better understood if we can make comparisons with modern analogues. Observations at Ponza imply that these pseudoclastic alteration features form synvolcanically or immediately after dyke emplacement and lava extrusion. This is compatible with scenarios presented for their formation in ancient sequences in the Mount Read Volcanics, Tasmania.

Jan 1, 1995

If a straight line should be drawn on the map (Fig 1) through the northern half of the South Island of New Zealand, from Mt. Domett in the north to Arthur's Pass in the south, and another line drawn parallel to it and at a distance of ten miles to thewest, according to the topographic scale, it will be found that within the belt thus drawn across the country all the most important mines, past and present, of the outh Island are situated, with the exception of a few in Otago.The most important product of this tract being gold, and Reefton, the most important southern mining field, being situated at about it central portion, the zone may aptly be termed 'The Great Reefton Gold Belt.'The occurrence of so many gold mines along this particular strip of country is not at all a matter of chance, but is the outcome of cause and effect. Running along the eastern side of the gold belt are the Brunner and Victoria Ranges, which are chiefly composed of crystalline schists and metamorphic granite of probably Cambrian or Silurian age; between these and the gold-bearing series there are interposed at one or two places some beds of slates, limestones, and cherts of Devonian age, characterized by the brachyopods Spirifer...

Jan 1, 1911

By Murdaugh W

The application of photogeological techniques and analysis of more advanced remote sensor images can be a cost and time effective tool in the search for desert placer gold deposits. Examples are given of regional analysis using standard false color composit Landsat images and conventional black and white aerial photography. The examples include identification of sites to sample to evaluate the pathways of .alluvial gold migration and identification of potential sites of concentration. The results of these studies developed an increased number of target areas and exploration in proceeding with promising results. In addition to the development of additional target concepts and identification of specific target areas data useful to evaluation of mineability can also be obtained from photogeological investigation. Some indication at least can be obtained of the existence of duricrusts and salines that may hamper mining. Identification of possible sources of water is another important task in the desert environment. In addition indications of the clay content of the material to be worked is very important because of its economic impact on operational costs and overall recovery. The application of photogeology to these questions is discussed.

Jan 1, 1988

By Fuller P. G, Miller D. R

Hydraulic fill using surface sand deposits or cycloned tailings has been used in underground mining for at least fifty years. Current technology requires a permeable fill and high cement additions for strong fill. Shortages in quantities of acceptable fill with finely ground ore may require rockfill or aggregate to be introduced as a supplement and these usually incur additional distribution costs. Alternative approaches to the problem are now being developed whereby the pulp density of the fill is raised so that it is delivered either as a dense slurry or as a paste. These regimes of fill behaviour are defined together with the plant and pumping techniques required to prepare and deliver the materials. Test techniques to define the different regimes of behaviour are identified and the variation in material properties for fills with varying pulp densities are outlined. The results indicate that high pulp density fills are stronger and have less permeability restrictions than conventional fills and that aggregate can be carried with the pulp. Thus the disadvantage of finer materials can be turned into an economic advantage. Criteria are developed for defining the type of operation suited to this Technology.

Jan 1, 1986

By Hannington MD

On the southern flank of Lihir Island, a group of three volcanic cones were discovered at water depths from 1000-1500 m. The volcanoes are located in a narrow zone of recent seismic activity and elevated heat flow (up to 100 mW/m2). The recovered rocks consist of fresh alkali-olivine basalts, clinopyroxene-rich basalts, and porphyritic phlogopite basalts. One of the volcanoes has a recently erupted ejecta blanket (recovery of warm ash!), containing a suite of abundant mafic to ultramafic xenoliths. These xenoliths appear to represent a unique cross-section of subduction- modified mantle material sampled by volatile-rich primary fore-arc magma during its ascent to the seafloor. The most spectacular finding was the discovery of an active hydrothermal system with associated vent fauna and mineralization at Edison Seamount, and the recovery of unusually gold-rich (up to 43 ppm Au) hydrothermal precipitates in 1050 m water depth at the top of Conical Seamount, only 25 km south of the world-class epithermal Ladolam gold deposit on Lihir. The discovery of submarine hydrothermal vents associated with highly alkaline, quartz-undersaturated fore-arc volcanics represents a significant departure from similar hydrothermal systems on the mid-ocean ridges and in back-arc basins. The high gold grades in hydrothermal precipitates at Conical Seamount may indicate the first documented example of a shallow-marine epithermal system analogous to those known on land, and has important implications for the gold potential of submarine arc environments.

Jan 1, 1995

It is very apparent that the hydrogeotogicat characteristics of mineral deposits in China be dominated by meteoric factors, terrain factors and the kind of karstic aquifers as a main source threatening the mining.The hydrogeotogicat characteristics of mineral deposits in dry areas are very different from that in non-dry areas.The rote of precipitation is very important to mine dewatering.The difference of water recharge condition of a mineral deposit located upper (or under) Local erosion basis is existing. There are more than two million square kilometers of carbonate in China.Many water-bearing deposits are distributed in it.According to the karst shapes the surrounding karstic aquifers of mines can be divided into three kinds including solution fissure aquifer,karstic cave aquifer and underground stream (karst stream) aquifer. Underlier invasion is a main feature of karst water-bearing coal mine and upper tier incoming is a main feature of skarn copper and ferro mine.Swatlor pillar and collapse is a special feature of karstic water-impregnated mine.

Jan 1, 1988

By Jones A

Today there is a vast amount of information available relative to the performance of tunnel boring machines, and associated systems. The data referred to here consists of project reports, manufacturer's equipment literature and papers concerning almost every aspect of the excavation process. Why is it then, that many projects that employ full face tunnel boring machines (TBMs), on average perform significantly less than the peak performances reported in this industry?

Jan 1, 1993

By S Tjerry, S Szylkarski, B Willis-Jones, I Dubinski

Achieving relinquishment of mining sites is becoming increasingly difficult, with a study by Byrne (2013) estimating that out of a set of 73 mining and metals sites around the world, less than ten per cent had achieved relinquishment over the last 50 years. The median forecast duration of time allocated for water management in the closure plans studied was approximately ten years, while the reality at the actual sites was a median duration of 22 years to date and growing.One of many challenges in mine closure planning is managing geomorphic stability of stream diversions. The challenge is to be able to demonstrate to regulators and the community that a proposed rehabilitation solution will be stable over the long term.During the mining operations, local watercourses and surface drainage can be diverted and managed using engineered channels and drainage structures. However, during the post-operations stage, the engineered channel and drainage may require modification to a more natural condition that will facilitate long-term environmental sustainability. Achieving geomorphic stability of a diverted watercourse is difficult, with the majority of stream diversions in Australia failing to meet expected design performance (White et al, 2013). Geomorphic stability is a complex process that is controlled by a combination of factors, including hydraulic flow conditions, geotechnical conditions and vegetation.This paper proposes that a fully dynamic and deterministic geomorphological model can be used to supplement the traditional empirical approaches to assess long-term geomorphic stability. The paper provides an overview of the geomorphological models and how they have been applied in engineering studies for forecasting future evolution of stream systems. The paper discusses the potential application of these models in the mining industry for forecasting and optimising surface water structures for the operations and post-operations stages of the mining cycle.CITATION:Szylkarski, S, Willis-Jones, B, Tjerry, S and Dubinski, I, 2016. Improving the reliability of stream diversion designs in mine closure plans using a morphological tool, in Proceedings Life-of-Mine 2016 Conference, pp 212–215 (The Australasian Institute of Mining and Metallurgy: Melbourne)

Jun 28, 2016

Tasker (1985) has detailed the accepted practices for constructing polygonal blocks of influerrce in the estimation of ore reserves. Further he suggests that users might fall into traps such as omission or overlap when determining the area of influence for each sample point.As an example of these types of errors Tasker (1985) describes under "Coverage ofthe Area" how 25 per cent of the exploration area will not be included in an equiangular triangular grid where hexagonal blocks of influence are used.The introductory suggestion of Tasker (1985) of "incorrect procedure" by Rudenno (1983) (and Armstrong (1983)) reiterated around the Figure 2a of Tasker (1985), is based on the brief description of the polygonal area of influence by Rudenno (1983). That description is not too different from that given by King, McMahon and Bujtor (1982).

Jan 1, 1985

By D Mukendi-Ngalula, G Hearn

Beach sand minerals from the volcanic rock structures of the Drakensberg, Kwazulu-Natal, (South Africa) have been processed. Screening, flotation, spiral concentration and magnetic separation methods were used either separately or successively in an attempt to concentrate monazite minerals. Products thereof and those from a long time (up to 72 hours) microwaves treatment of the finally produced ilmenite-bearing minerals have been studied using the M÷ssbauer effect spectroscopy. The 57Fe M÷ssbauer effect spectroscopy has demonstrated its versatility and power in monitoring the ilmenite internal reduction mechanism and products and, in characterising the iron-bearing phases contained in different products from the beach sand minerals processing. Microwaves heating of ilmenite for up to 38 hours reduced internally the Fe3+ from the ilmeniteÆs structure. A more prolonged microwaves heating (up to 72 hours) re-oxidised the mineral. 61 per cent natural ilmenite recovery was obtained in the floating products of a spiral concentrated -212+106 ¦m screened and beach sand minerals fraction. A preferential concentration of hematite with a 62 per cent recovery was found in the sinking products while the combination of screening-spiral separation-magnetic separation and flotation yielded a floating product with the highest ilmenite and the highest hematite abundanceÆs (71 per cent, 19 per cent respectively). A natural ilmenite containing 87 per cent ilmenite and 13 per cent hematite could be produced and extracted from the sinking products of the flotation process collected subsequently to the spiral concentration and the initial screening.

Jan 1, 2000

By S C. Dominy

Gravity amenable gold ores are those that after comminution produce liberated particles, composites and/or carriers that can be recovered by gravity separation means. Recovery depends upon mineralisation type and the comminution and concentration method used. Any in situ ore with more than 20 per cent of gold greater than 100 µm in size is likely to have a strong gravity recoverable component. A less traditional approach is where the gold is sulfide-locked and the gold carrier plus any liberated gold is recovered via continuous gravity recovery following fine crushing. Specific tests are undertaken to determine the level of gravity amenable gold within a deposit. The principal methodology is the gravity recoverable gold (GRG) test, which consists of three sequential liberation and recovery stages. For continuous gravity recovery (CGR), the sample is fed over a laboratory Wilfley table to simulate continuous recovery of the gold. Tails from the feed can be progressively re-ground and re-tabled to develop a grade-recovery curve. Primary geology and gold particle size-distribution have a strong effect on the mass of sample required to provide representative results for both tests. Where low-grade ore contains very coarse gold, substantially larger sample masses are required. Experience has shown that GRG and CGR values can vary throughout an orebody, particularly within different geological-grade domains. A testing regime must consider sample frequency and support.

Sep 5, 2011

The AusIMM came into being to foster the spread of professional knowledge within its client industry. It has evolved along with the Australian mining industry for more than a century. If the AusIMM is to become the world's premier mining professional body (whether by design, or by default), then draw up a strategic plan to get there. Define your strengths and market them Define the priority areas for professional competence which we most need, Target the groups within Australia who can produce the people, Create an industry peer group to speed technology transfer.

Jan 1, 1994

By N Petropoulos and M J Thurley, E Righetti, M Wimmer

Fragmentation in sublevel caving (SLC) is vitally important. Both gravity flow and any downstream processes are affected. Reasonably coarse fragmentation may lead to larger draw bodies (isolated extraction zones) and hence potentially higher primary ore recovery and depressed/delayed waste rock inflow from above. Fewer flow disturbances are expected by mitigating oversize. In addition, it requires less boulder handling and reduces wear and possible hang-up problems in orepasses. To assess the present-day functionality of large-scale SLC, a multiyear, comprehensive measurement program was initiated. It covers the main elements for SLC, namely blast function, fragmentation and gravity flow. The present paper focuses on fragmentation measurements. An image acquisition system was used to document the drawpoint and the load-haul-dump (LHD) bucket for each mucking cycle. At the beginning, four buckets (about 70 t total) were sieved to validate the results of both 2D and 3D image analysis techniques. The fundamental and specific problems are discussed herein. At the moment, fragmentation of the SLC rings is evaluated using a quick rating system and a 2D fragment delineation software. The results enable a description of fragmentation and its variation during mucking but also – combined with the gravity flow measurements – conclusions on the fragmentation for different parts of the SLC ring. Possible influences on flow disturbances and ore recovery/dilution are investigated. The recent findings allow a better understanding of breakage and flow and support future process improvements.CITATION:Wimmer, M, Nordqvist, A, Righetti, E, Petropoulos, N and Thurley, M J, 2015. Analysis of rock fragmentation and its effect on gravity flow at the Kiruna sublevel caving mine, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 775–792 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By Weatherstone N

Ironstone outcrops on the Savage River were discovered by State Government Surveyor C. P. Sprent in 1877. The limonitic outcrops were initially regarded as the surface expressions of pos- sible tin-bearing lodes, the tin deposits at Mt. Bischoff to the east having been found in 1871. By the turn of the century, shafts, adits and trenches had been developed on the deposits in the unsuccessful quest for gold, silver and base metals. The deposits were first reported as a possible source of iron ore by Tasmania Department of Mines (TDM) geologists in 1919. Modern exploration began in 1956 with the area registering the best magnetic response during an aeromagnetic survey of North- western Tasmania by the Bureau of Mineral Resources (BMR). The area had previously been reserved by TDM in anticipation of the lifting of the iron ore embargo. Reconnaissance Geologi- cal mapping (TDM) and grid-based magnetometer surveys (BMR) indicated that resources of iron-bearing material could approach hundreds of millions of tons. This provided the incentive for two diamond drill holes funded by TDM which demonstrated iron mineralisation in substantial tonnages, suitable grades and, fol

Jan 1, 1988

Digitally enhanced Landsat MSS images are being used'in delineating the structural and tectonic features in the Arabian Shield as part of a project funded by King Abdulaziz City for Science and Technology (KACST) of Saudi Arabia. The delineated features together with statistical modeling and structural analysis are to assist in an improved understanding of the evolution and mineralization of the Arabian Shield. Specific emphasis is to be given to relating the extracted linear features to the location of known mineral occurrences and areas of potential geologic hazards. A number of textural (spatial) and spectral enhancement techniques have been applied, to the MSS data covering selected areas, in selecting the most optimal enhancement product for visually delineating the structural geologic .features.

Jan 1, 1988

By Dagbert M, Belisle J. M

Several packages for the estimation of porphyry type deposits exist and produce acceptable results. Recently, however, the need for really trying to obtain maximum information from drill holes has prompted the generation of geostatistical solutions to the problem of reserve calculation. It will be shown that an understanding of a few key points is necessary in order for these solutions (variogram analysis and kriging) to he really ptimal. The most important new fact to be ecognized in open pit ore reserve estimation is that block models do not give an accurate rediction of ore tonnage when a cut-off is pplied but often yield an overestimation of p to 25%. When checked against extensive roduction records, geostatistical methods provide a practical solution to this problem. t now seems that the model used here gives he best possible results. Inasmuch as all arge deposits present very similar geostatis- ical characteristics only a few days of work re necessary to produce a complete inventory f these. The techniques used will be demon- trated using examples from five deposits and pecial emphasis will be given to the accurate rediction of tonnages of ore and waste using he new "transfer function" technique of G.

Jan 1, 1977

By J Li, A McFarlane, J Yu, L L. Kuhar, R Meakin, N Chapman

"Column leach tests are used frequently to predict recoveries and reagent consumption for nickel laterite heap leaches. These column leaches often run for more than 100 days and therefore require long-term monitoring and data analysis to achieve the desired information. To minimise the cost and time required to obtain relevant information for nickel laterite heap leaching, we have developed a small-scale hydrogeometallurgical laboratory test to serve as a proxy to column, and by inference, heap leaching. In excess of 50 leach tests were conducted using four different small-scale proxy and column leach tests to compare predicted nickel recoveries, acid consumption and leach kinetics and to determine whether insight into potential scale-up effects can be obtained. The most promising proxy test was identified and we achieved a statistically significant recovery and acid consumption correlations between this test and the column leach tests. The accuracy of the small-scale tests was confirmed by column tests run on new laterite ores. This geometallurgical proxy could be of use for the population of block models and process selection during the mine planning phase or for optimisation and control during processing.CITATION:Li, J, Kuhar, L L, Meakin, R, Chapman, N, McFarlane, A and Yu, J, 2016. A Geometallurgical Proxy for Nickel Laterite Heap Leaching, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 335–340 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

The QSL continuous lead smelting process incorporates two basically different pyro- metallurgical operations: roast-reaction, smelting of galena concentrate, followed by carbothermic reduction of some by-product lead oxide slag. Both steps are performed simultaneously in separate compartments of a long horizontal cylindrical reactor, which is lined with fused chrome-magnesite bricks. This converter-type reactor contains a liquid bath consisting of a shallow layer of lead bullion with a superimposed layer of slag, the lead content of which is gradually reduced from about 50% to discardible levels. Metal relative to slag, and slag relative to the gas phase are in continuous countercurrent motion. A lead well is arranged at the flue end of the reactor, and an overflow tap for slag at the opposite end. Tonnage oxygen for oxidation and smelting of the charge, and sub- stoichiometric mixtures of pulverized coal and oxygen for reduction and heating of the slag, are directly blown into the bath using fluid-protected Savard-Lee injectors. High gas-liquid momentum transfer ensures intensive local mixing, and enables rapid mass and heat transfer.

Jan 1, 1984

By B R. Bittencourt, D A. B Pasin, D Pi

Three main genetic types of hematite can be recognised at Quadrilßtero Ferrffero (QF): Micaceous or schistose hematite derived by metamorphic/metasomatic process during regional metamorphism, increasing eastward, formed under temperatures ranging from 250¦C to 500¦C in CO2-rich aqueous carbonic, high- to medium-salinity fluids. Hematite in shear and mylonite zones, showing a wide variation of fluid and temperature conditions, between metamorphic and hydrothermal conditions. Deformed quartz-specular hematite veins formed during the late phases. Hydrothermal, compact and isotropic hematite developed during a brittle-ductile regime, forming the cement of the boudinage-kink breccia and jacutinga-type of gold mineralisation, under temperatures ranging from 80¦C to 140¦C in aqueous, low- to medium salinity, oxidant fluids, resulting from the interaction of meteoric and metamorphic/metasomatic fluids. Quartz-carbonate-sulfide veins were formed slightly later, through reducing fluids.

Jan 1, 2005