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By Hocking G

For some underground structures, the use of the plane strain assumption in stress analyses may not be justified. The finite element method and photoelasticity have been used to obtain complete 3-D solutions, but, for various reasons, neither method has found universal use. The boundary integral equation method (B.I.E.M.) can be more efficient and economical than the finite element method for 3-D problems involving large volume to surface area ratios. A B.I.E.M. program developed for calculating stresses and deformations in infinite elastic media has been used to determine the 3-D distributions of stress around T- and Y- junctions of circular tunnels in stress fields in which the ratios of horizontal to vertical stress are 0, 0.33, 1.0 and 2.0. For the T- junction considered,stress concentrations at the intersection are approximately twice the plane strain values. Except where horizontal field stresses are high, the stresses in both tunnels approximate the plane strain values at about two tunnel diameters from the point of intersection of the tunnel centre lines. The stresses in the two branches reach those for the corresponding plane strain, two parallel tunnel case two diameters from the point of intersection of thq inner tunnel walls. Very high stress concentra- tions occur in the pillar of rock between the inner tunnel walls near the point of intersection.

Jan 1, 1976

By Robinson B, Ham B

Outbursts have occurred irregularly in the Collinsville Coal field since 1954 when an incident claimed seven lives. Further significant outbursts occurred in 1960, 1961, 1972 and more recently in the No. 2 mine in 1978. From the information collected over 25 years a comprehensive program to minimize the hazard of outbursts has evolved. Further developments of techniques to combat outbursts are being developed.

Jan 1, 1980

Traditional in situ fan flow test methods under accepted standards require determinations to be made of both static pressures and total pressures during testing. This is to determine the resultant velocity pressures, which are vital in the accurate determination of the final fan airflow. These crucial velocity pressure (Vp) determinations are normally determined using simple manometric instrumentation such as an electronic manometer or an inclined liquid filled manometer. There is relatively little noise or fluctuation in the static pressure determinations and they can be quite easily and accurately recorded. There is almost always considerable fluctuation in the velocity pressure determinations though due to the highly turbulent and irregular velocity profile normally found in such in situ installations. This velocity turbulence means that the recording of such data is subject to random human error as the observer tries to average such fluctuations mentally during the observation period. Worse than this, and in the extreme, the recording of such velocity pressure data could actually easily be misreported if, for some reason, persons chose to do so.The author has devised a field method using highly accurate quartz crystal logging barometers to objectively record these velocity pressures. The method eliminates the ability to either mistakenly or intentionally misreport these crucial velocity pressures and is carried out in parallel with the recognised methodology, so result comparisons can be drawn. As such, a far greater level of confidence can be achieved in the final flow performance results than using the traditional more subjective method. Further to this it is difficult and almost impossible to refute the results using this ancillary substantiation method.The accurate determination of fan flows due to the impost of the carbon tax has taken on much more significance given the financial impacts in Australia at this time. The methodology detailed herein can be applied equally for both fan flow compliance testing and the verification of mine airflow data for greenhouse gas emission evaluations.The paper utilises the results of one 24-point pitot traverse to demonstrate the various findings. These include the very wide range of velocity pressures, which were logged at most of the measuring stations. It also illustrates how the method is utilised and compares the results derived from both this method and the more subjective traditional method along with the benefits of logging the velocity pressure results during the testing process.CITATION:Rowland, J A, 2013. Removing some subjectivity from traditional BS 848 and ISO 5802 in situ fan flow tests, in Proceedings The Australian Mine Ventilation Conference , pp 155-162 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 1, 2013

By P J. Howard, P Darvall, J H. Mainwaring

In less than a year, Atlas Iron’s Corunna Downs Project has moved from a new discovery to a substantial resource of high quality in an underexplored greenstone belt. Located approximately 170 km south-east of Port Hedland and 40 km south-west of Marble Bar, in the Pilbara Region of Western Australia, Atlas Iron Ltd (Atlas) has conducted extensive exploration work at Split Rock, Razorback, Runway and Shark Gully, consisting of geophysical surveying, field mapping, 464 reverse circulation and 16 diamond drill holes resulting in a current resource of 51 Mt at 57.3 per cent Fe (Atlas, 2014b).The Corunna Downs Project is interpreted to be hosted within the Cleaverville Formation of the Archaean Gorge Creek Group. Within the project area these rocks outcrop as subvertically dipping banded iron-formations (BIFs) and jaspilites, cherts, minor shales and meta-sediments forming a north–south trending plateau.Primary hematite-martite iron mineralisation is overprinted in the near surface environment by supergene goethite, and frequently capped with a thin laterite cover. The strongest enrichment areas have been discovered within topographic lows, proximal to fault zones, which coincide with a geophysical anolmaly. These characteristics were targeted, and the subsequent areas mapped in greater detail, allowing for efficient resource definition.Although first explored for iron in the late 1960s, it wasn’t until Atlas’ acquisition of the project in October 2012, that major strides were made to defining an economic resource. At present, Corunna Downs is Atlas’ best greenfields exploration discovery, both in terms of the potential scale of the resource and its blending capacity.The Corunna Downs prospect is emerging as a major new iron ore province in the Pilbara and includes 80 km of potential host stratigraphy. Corunna Downs sits strategically between Atlas’ Mt Webber and McPhee Creek tenements, and can play an important part in Atlas’ growth strategy as iron ore market conditions become more volatile and challenging.CITATION:Mainwaring, J H, Howard, P J and Darvall, P, 2015. Discovery of the Corunna Downs deposits, in Proceedings Iron Ore 2015, pp 305–312 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

In 1972, metallurgical testwork on Renison ore indicated a significant proportion of low specific gravity, tin-barren material ideally suited to heavy medium separation (HMS). Further technical and financial studies provided adequate economic justification and in December 1974 the Renison HMS plant was cannissioned. Initial operations were interrupted by the imposition of tin production quotas for three months in 1976; they were also beset with difficulties particularly with regard to mechanical wear. During the first two operating years much develognent work was carried out including installation of a pyrrhotite flotation bank in the medium recovery circuit, investigations into various wear-resistant materials and the use of atanised rather than milled ferro-silicon. By 1977/78 financial year satisfactory performance had been achieved and since then the average floats rejection has been 18.8% of the total ore treated with an associated tin loss of 2.96%. Developnent has nevertheless continued during the last three years, principal modifications being the installation of larger aperture desliming screens and improvements to the overdense cyclone circuit.

Jan 1, 1978

By Gross A. E, Neville P. C

Over the last decade heap leaching with a cement binder has allowed the economical leaching of low grade gold ores of less than 2 grams/tonne. Despite the continued use of cement as an agglomeration aid, numerous leaching operations continue to experience channelling and blinding problems. This paper describes the development of polymeric agglomeration aids, Extract Ore 9760 and 9960, which when used as a partial cement or lime replacement can result in a higher rate of and/or a higher total gold recovery in plant evaluations. Extract Ore in combination with cement acts to produce a stronger agglomerate which results in reduced fines migration during leaching and helps prevent blinding of the heap. Both of these changes will give a more even flow of cyanide solution throughout the heap and improve solution contact efficiency within the ore. Polymeric agglomeration aid programs are now being used by heap leaching operations in three different countries. A summary of benefits identified at some of these operations are presented in this paper.

Jan 1, 1994

By Green S, McKernan, Skrypniuk

In November 1996, Boddington Gold Mine (BGM) began the implementation of an expert system. The objective of the expert system was to improve plant efficiency by developing an `operator best practice' control philosophy for the grinding circuit

Jan 1, 1997

Expert systems are a product of Artificial Intelligence (AI), a field of long standing, dedicated to the study of problem solving using heuristics, construction of symbolic representations of knowledge about the world, communications proce

Jan 1, 1998

By B Taylor

The Perseverance deposit is the most southerly known economic copper/gold deposit within the Cobar gold field. The deposit is situated approximately 12 km to the south-southeast of Cobar and is essentially blind to surface with the top of economic mineralisation occurring 750 m below ground level.Based on the December 2010 resource estimate (inclusive of reserves and net of depletion) the deposit contains 3 011 000 tonnes at 6.1 g/t Au and 0.90 per cent Cu (590 000 oz of gold and 28 000 tonnes of copper). The deposit is comprised of four principal lenses, the Perseverance, Hulk, Zone B, and Hercules lenses. In excess of 90 per cent of the known resource tonnes are contained within the Perseverance and Hulk lenses. The deposit is shear related and hosted within lower Devonian rocks of the Cobar Basin. The competency contrast of rhyolites juxtaposed against sediments by the Peak-Perseverance shear is the principal control on mineralisation. Both the Perseverance and Hulk lenses are primarily hosted by brecciated rhyolites juxtaposed against Chesney formation sediments across the Peak-Perseverance shear. This faulted rhyolite sediment contact roughly defines the global orientation of the deposit. The Perseverance lens continues within the shear for up to several hundred metres beyond the extent of the faulted rhyolite sediment contact. Mineralisation within the shear beyond the faulted rhyolite contact zone is hosted by sheared silicified sediments. The Perseverance lens remains open at depth and to the south.The Zone B and Hercules lenses, which are significantly less important in tonnage terms, are hosted by rhyolite breccias within the main body of the rhyolite and appear to be only tenuously related to the Peak-Perseverance shear. Within the Perseverance lens, the presence of northeast trending high grade breccia veins developed oblique to the north-south trending shear system has led to the development of steeply north plunging high grade ore shoots within a globally north-south trending mineralised domain. These high grade shoots have limited horizontal continuity but significant down plunge extent.The presence of coarse gold and the resulting strongly skewed nature of the gold grades, in conjunction with controls on mineralisation which are not parallel to the mineralised domain, has led to predictive difficulties regarding stope performance.Strong heterogeneity of the gold content of the ore and geological controls on mineralisation which are not parallel to the global trend of the mineralisation impose a set of difficulties which sound geological control is helping overcome.

Aug 22, 2011

By P G. Greenhill

The Wonawinta silver project near Cobar in NSW is under development by Cobar Consolidated Resources Limited (CCR). RMDSTEM Limited is part of the owner’s team for feasibility, design, engineering, construction and commissioning.With a 51Moz resource CCR is one of the largest pure silver players in Australia. A probable reserve of 14.3Moz has been defined for a mine life of approximately five years. The silver mineralization is contained in host rock composed of clays and oxidized limestone. The ore also contains on average 1.3% lead as cerussite, and other minerals. A simple circuit consisting of slurrying of the ore, gravity treatment of the coarse fraction to recover lead, silver extraction using CIL, elution and the Merrill Crowe silver recovery process, has been developed.The “value engineering” approach to this development pioneered over the past decade by RMDSTEM has meant that RMDSTEM has delivered the bankable feasibility study at a cost of $0.07 per resource ounce. It is highly cost effective making efficient use of shareholders funds as well as being very time efficient. This paper describes the application of the value engineering approach to the development of the Wonawinta project.

Aug 8, 2011

By J White

The Eyre Peninsula (EP) has been known for its iron ore for more than a century. Edward John Eyre noted the ironstone outcrop at what is now Iron Knob in the 19th century. Sir Douglas Mawson visited and reported on the geology of the lower EP in 1906, noting the widespread presence of iron stone and the likelihood of copper being associated with the iron stone. Despite this knowledge there has been only one successful iron ore mining region developed on the EP and that is Iron Knob and the Middleback Ranges which have been mined continuously since 1899. The Middleback Ranges can justly lay claim to be birth place of the Australian iron ore and steel industries.The discovery of large scale haematite resources in Western Australia meant that there was no need to seek out iron ore that needed benefi ciation. The low price of iron ore precluded further development of the EP and many other areas in Australia and overseas. This situation changed rapidly in the mid-2000s with the emergence of China as the world’s industrial power house and the soaring demand and price for many resources including iron ore. This triggered a flurry of activity across Australia and led to the rapid exploration and drives to develop the EP iron ore. A brief examination of the magnetic maps of the EP shows the wide spread presence of magnetite and associated smaller haematite deposits. A closer look reveals the magnetite deposits to vary in formation style and host rock lithology as well as being significantly altered by regional metamorphism. *This is an abstract only. No paper was provided for this abstract.*

Jul 11, 2011

In Mount Isa voltage and frequency fluctuations caused. by haulage shaft operation gave considerable difficulties with the initial application of Atomic Absorption Spectro-photometry.The methods used to stabilise the various units ' have been described.- Some other difficulties and the means used to eliminate or reduce them together with a-modified burner design are also discussed.

Jan 1, 1963

Five types of mineral resource were known in the sedimentary cover of the oceans and seas floors prior to the 1980's :1) hydrocarbon fields including some very large zones of oil and gas accumulation; 2) "Red Sea" type thermal oozes with increased concentrations of noble metals; 3) ferromanganese nodules; 4) concentrations of metallic sulphides ("Black Smokers"); and 5) cobalt-bearing ferromanganese crusts on the summits and slopes of seamounts. Since then, the so called "White Smokers", containing sulphides of copper and zinc, have been discovered. The ore horizons (manganese, copper, nickel and other metals) of the sedimentary cover of deep-sea basins comprise a sixth type of mineral resource in the oceans. These horizons have not only a theoretical, but also a principal economic significance

Jan 1, 1995

By N J. Grigg

Gekko Systems has developed an underground pre-concentration plant (Python) to reduce mine operating costs. Many ores liberate favourably using either high pressure grinding rolls (HPGR) or vertical shaft impactors (VSI). Using these comminution circuits for mineral liberation; rather than for the final recovery process and by utilising a high mass pull, high recovery process route (gravity/flotation), a narrow, low head, compact processing plant was developed that can sensibly be operated underground. The Python underground processing plant can provide a number of advantages for narrow vein mines including lower haulage costs, improved mine call factor and lower operating costs. The focus on fine crushing reduces the power requirement of the plant to approximately 8 kWh/tonne. The Python underground processing plant has been designed to be towed down the decline or lowered down a shaft, and is capable of being installed in sloping, non-linear drives for placement close to the working face. The overall benefit to mining companies of this concept has been estimated to be a saving in mining costs and a significantly smaller environmental footprint.

Jan 1, 2008

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

Developments in furnace construction and design have been very rapid in recent years. Larger furnaces operating at high top pressures with much improved burdens are giving extremely high production rates. Modern scientific techniques and the use of computer control are contributing to these Rates.

Jan 1, 1972

By Knasmillner

During blasting body wave interaction with geometrical surfaces induces Rayleigh-waves which propagate along free surfaces, e.g. crack faces or delaminated rock layers. These Rayleigh-waves carry most of their energy within a very shallow surface layer and propagate with very little attenuation in real rock materials. Upon interaction with a crack front a very strong mixed mode stress intensity factor may result and lead to fracture initiation. On the basis of experimental photomechanical results the history of dynamic stress intensity factors Kt and K2 will be studied in Detail.

Jan 1, 1990

By J Jackson

The term geometallurgy (or geometallurgical) first appeared in the literature some 40 years ago and has a wide range of definitions and perspectives which increases the barriers of communication between practitioners and across functional groups and management levels within organisations. However the consistent theme running through the diversity of definitions and perspectives is the requirement for close collaboration between the relevant disciplines. This concept of geometallurgy arguably goes back to the earliest days of the exploitation of mineral deposits, through the mid-1500s to the beginning of the 20th century.This holistic and integrated view was diminished during the 20th century due to a number of factors which included the commencement and continuing upward trend of large-scale mining and the expansion in production, the rise of scientific and classical management theories and methodologies, increase in specialisation and the development of traditional project planning. The re-emergence of geometallurgy in the late 20th century required the relevant functional units and disciplines to collaborate as a team. This necessitates a common understanding that the geometallurgical program’s goals must be obtained, which requires clear and consistent communication, particularly with the modern trend of virtual teams.A multi-dimensional construct is proposed to assist in providing a consistent approach in the communication of the context and purpose of both general and specific geometallurgical programs, thus simplifying communication. This geometallurgical construct consists of the dimensions of process span, response knowledge, variability knowledge, spatial knowledge, application and project phase in relation to extraction process(es) applied to geological materials from a mineral deposit. These dimensions are then linked to the phase of mineral project development in which the geometallurgical program is being applied, which ranges from advanced exploration through to operational execution. This paper outlines the multi-dimensional construct with examples of how the context, purpose and scope of geometallurgical programs can be clearly delineated and communicated.

Sep 5, 2011

By A M. Suchowerska, J P. Carter, J P. Hambleton

"In order to effectively predict the roof collapse of underground openings using continuum models, it is imperative that a realistic failure criterion is used to represent the rock mass. However, for coal mining operations, there is still uncertainty as to the appropriate failure criterion that should be used for the coal measure strata. This study compares stability numbers and collapse mechanisms for a rectangular underground opening predicted based on three commonly used failure criteria: the standard Mohr-Coulomb, Mohr-Coulomb with a tension cut-off and Hoek-Brown. Three methods of analysis are considered: an analytical upper bound method an upper and lower bound finite element formulation the displacement finite element method.The theoretical results are also compared with field measurements of subsidence above longwall coal mining. For the standard Mohr-Coulomb failure criterion, the friction angle governs the shape of the collapse mechanism, and the so-called critical width (the cavity width above which failures extend to the ground surface) ascertained from field observations in the New South Wales coalfields corresponds to a friction angle of approximately 30°. On the other hand, predictions obtained based on the Hoek-Brown failure criterion consistently overestimate the critical width. The results also show that tensile failure governs the stability of the cavity and shape of the collapse mechanism when a tension cut-off is introduced for the Mohr-Coulomb yield criterion.CITATION:Suchowerska, A M, Hambleton, J P and Carter, J P, 2014. Prediction of roof collapse for rectangular underground openings, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference, pp 367–374 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Nov 5, 2014

The Pilbara region, located in the north-west of Western Australia, is significant as the second-largest source of iron ore on the planet. Iron ore mines owned and operated by Pilbara Iron are located within the Hamersley Basin. This paper refers to the Greater Paraburdoo mines, the 4WEST and 4EAST pits, located on the southern margin of the Hamersley Basin. The groundwater model refers to ephemeral watercourses: Seven Mile and Pirraburdoo creeks, which are adjacent to the two pits, and Ratty Springs, located upstream from 4WEST and within Pirraburdoo creek. The spring and creeks hold cultural heritage significance for local Aboriginal communities. Two of these, the Gobawarrah Minduarra Yinhawanga (GMY) and Innawonga native title claim groups, initiated hydrological work on the two creeks and Ratty Springs, with the aim of determining the affects of dewatering on the natural water flows of these systems. The numerical model used to simulate drawdown in the Pirraburdoo and Seven Mile Creeks was derived from PMWIN Pro software and covered an area of 77 km2. The modelling period was from January 1998 to December 2004, and the prediction period was from January 2005 to December 2015. The model has four layers and incorporated effects caused by mining voids, 4WEST and 4EAST pits, creek bed material, weathered bedrock below creeks and surrounding banded iron formations (BIF). The model has been calibrated using the trial-and-error method set down by Middelmis et al (2001). The current dewatering schedule (12 ML/day) in the 4WEST and 4EAST mining areas does not affect the water table levels in the adjacent creeks significantly or for any considerable periods of time. However, changes to mine plans may occur, for example, in response to changed commodity price and may lead to significant increase in rates of vertical advancement. This, in turn, affects dewatering schedules, as greater vertical advancement requires increased dewatering effort. When an accelerated mine plan is applied to the model and dewatering rates increased to 18 ML/day, drawdowns in the creeks are more noticeable. The model has therefore helped to indicate the extent to which increased dewatering rates may be acceptable, especially in terms of immediate and longer-term damage to riparian species, ie Melaleuca and Eucalypt. Predictions from the model may also allow mine planners to schedule decreased rates of vertical advancement, where these are required to meet environmental constraints.

Jan 1, 2006