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By D Craw, P V. Angus

Gold mineralisation at Macraes occurs as late quartz-carbonate veins within a body of sheared and hydrothermally altered Otago Schist, the Intrashear Schist. The alteration is characterised by the presence of rutile and the absence of epidote and titanite, indicative of an alteration fluid containing >10 mol per cent CO2. In areas of high strain, a fabric of black microshears develops, gradational to mylonitic cataclasite in the high strain zone adjacent to the hanging wall of the duplex shear zone. The microshears contain hydrothermal graphite, inferred to have been deposited from a methane-rich fluid. The mylonitic cataclasite is characterised by abundant pyrite, the absence of albite and extreme grain size reduction. Gold recovery in the CIL processing plant at Macraes can drop to 50 per cent or lower for some unfavourable ore types. Preg-robbing by a component in the ore, possibly graphite, was suspected as the cause. Mylonitic cataclasite was identified as the lithology responsible for the poor recoveries, with the capacity to bind about 30 ppm of gold in the leach tanks. A program of detailed geochemistry and quantitative grain-size measurement using Coulter analysis was undertaken to identify specific mineralogical factors associated with preg-robbing. The results indicate that pyrite, graphite, and extreme grain-size reduction are the factors associated with highly preg-robbing ores at Macraes. The evolution of the mylonitic cataclasite is accompanied by strong potassium enrichment, as muscovite, and depletion in sodium as albite is removed. This suggests that a simple powder XRD ratio of the albite to illite peaks would suffice to distinguish the preg-robbing ore for grade-control purposes.

Jan 1, 1999

The Division of Minerals and Geochemistry in collaboration with three mineral exploration companies, Mawson Pacific Ltd, Ramsgate Resources Ltd and Tectonic Systems Pty Ltd commenced a two year research project to investigate the application of remote sensing techniques to exploration for mineral deposits in access of the Yilgarn Block in Western Australia. The project utilizes satellite data such as day and night imagery from the NOAA-AVHRR (National Oceanic and Atmospheric Administration - Advanced Very High Resolution Radiometer) satellite. The recent research with the imagery in the Kalgoorlie, Southern Cross and Mt Magnet regions has highlighted the advantages of the mid infra-red and the two thermal response channels of NOAA-AVHRR for geological investigations. These three channels have the spectral resolution to distinguish stratigraphic units and younger intrusive bodies, and to delineate fracture zones and shear zones associated with Proterozoic dykes. But most important is the capacity to distinguish thermal signatures from geological structure, near-surface outcrop and palaeochannels which have been covered by unconsolidated sediments. The research project applies remote sensing methods including enhanced satellite imagery optimised to the Western Australian environment. It encompasses data from both space and airborne monitoring platforms that have obsreved a significant spectral response for the classification of alteration zone lithologies. It includes the collection of multiseasonal data from areas of interest which is essential both for the understanding of thermal characteristics of important lithologies and for the extrapolation from field work investigation to potential exploration areas. No comprehensive investigation of this type has been carried out within the Yilgarn goldfields.

Jan 1, 1987

By A Manzoori, M T. Shadloo

This paper describes a CFD modelling study which was carried out to investigate possible improvements in the design of an alumina precipitator tank at the Jajarm plant of Iran Alumina Company. In particular, the tank has an impeller located very close to the tank bottom, such that it quickly becomes covered with settled solids after a shut-down of the agitator, making it difficult to restart. A CFD model was firstly set up in which the existing design was evaluated in terms of flow pattern, off-bottom suspension and distribution of solids, and power consumption. Further simulations were then carried out to test alternative designs, leading to a recommended design, which maintains good mixing, with the same power consumption and without the use of a low-clearance impeller.

Jan 1, 2006

By Bell I. F

In 1985, ZC Mines (now Pasminco South) had been unprofitable for some years due to a combination of high operating costs, low metal prices, low head grade and an aging and inadequate mining infrastructure. However, the resource of metal in the ground was still of world class, even after some 80 years of mining. A major study, which was to be of two years duration, was therefore commenced to establish a practical and profitable long term mining strategy and to cost the infrastructure options needed for its support and thus form the justification for a capital expenditure program to take the mine profitably into the 21st century and its second century of operation. This paper discusses the rationale behind the methodology adopted and the nature of the results achieved in one aspect of the study - the determination of the mineable resource and the relationship between the head grade/quantity of the economically mineable resource and the variables of cut-off grade, cost structure, annual production rate and metal prices/exchange rates. The basis of the study was the designing of some 5000 scopes to mine out the entire resource for a range of cut- off grades and the assembly of the detailed physical data thus obtained in a stope-by-stope data base for financial and other analysis. Those scopes which were shown to be economically mineable were then scheduled for two optimum annual production/cut-off grade/metal price combinations to provide life-of-mine cost and value of production cash flows.

Jan 1, 1992

By A Woodley, G Keir

The mining industry faces concurrent pressures of reducing water use, energy consumption and greenhouse gas (GHG) emissions in coming years. However, the interactions between water and energy use, as well as GHG emissions have largely been neglected in modelling studies to date. In addition, investigations tend to focus on the unit operation scale, with little consideration of whole-of-site or regional scale effects.This paper presents an application of a hierarchical systems model (HSM) developed to represent water, energy and GHG emissions fluxes at scales ranging from the unit operation, to the site level, to the regional level. The model allows for the linkages between water use, energy use and GHG emissions to be examined in a flexible and intuitive way, so that mine sites can predict energy and emissions impacts of water use reduction schemes and vice versa. This paper examines whether this approach can also be applied to the regional scale with multiple mine sites.The model is used to conduct a case study of several coal mines in the Bowen Basin, Australia, to compare the utility of centralised and decentralised mine water treatment schemes. The case study takes into account geographical factors (such as water pumping distances and elevations), economic factors (such as capital and operating cost curves for desalination treatment plants) and regional factors (such as regionally varying climates and associated variance in mine water volumes and quality).The case study results indicate that treatment of saline mine water incurs a trade-off between water and energy use in all cases. However, significant cost differences between centralised and decentralised schemes can be observed in a simple economic analysis. Further research will examine the possibility for deriving model up-scaling algorithms to reduce computational requirements.CITATION:Keir, G and Woodley, A, 2013. Regional trade-offs between mine water and energy use - a water treatment case study, in Proceedings Water in Mining 2013 , pp 21-28 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 26, 2013

Since gold was first discovered, mining development in the West Australian goldfields has been heavily dependent on the location of groundwater both for potable and mineral processing supplies . The location of adequate and economic sources of water has been a constant challenge to both explorers and developers throughout the history of the goldfields. The provision of a piped supply from Mundaring in 1903 greatly alleviated pressure on scarce resources, lowered mining costs and permitted the orderly development of infrastructure. However, increases in the demand for water resulting from new mineral discoveries over the past three decades has led to renewed pressures for more local supplies to be established. Wide-ranging groundwater exploration took place in the late 1960's and early 1970's, also, more recently, in support of intensified gold exploration. The collation and interpretation of the hydrogeological data from the whole goldfields region indicates that despite a low mean annual rainfall of between 180 and 350 mm, quite marked differences exist between the rates of groundwater recharge in different parts of the area, In general, these can be shown to diminish in a southerly direction contrary to a trend towards increases in annual rainfall. Recharge rates are related mainly to differences in rock weathering pattern, geological structure and physiography. The same differences have controlled the pattern of groundwater salinity and the magnitude of groundwater storages associated with the palaeodrainages. In the vicinity of the northern and western watersheds with the Gascoyne, the superficial sediments tend to be thin, may have calcrete in the section and contain moderate storages of brackish or even fresh water. This contrasts with the lower regions of the palaeodrainages where calcrete is absent and deeper erosion has permitted the accumulation of relatively large thicknesses of fine-grained sediments which are saturated with hypersaline water and constitute substantial storages. Account must be taken of these characteristics if water supply sources are to be optimised to meet the growing demands for groundwater in the region.

Jan 1, 1988

By P Pieterse

Kumba Iron Ore Ltd is currently commissioning the Sishen Expansion Project (SEP) û a brownfields project on the Sishen Iron Ore Mine located in the Northern Cape Province, South Africa. SEP is designed to produce 13 Mtpa of product from 21.7 Mtpa of ROM feed. The beneficiation section of SEP employs jigs to process narrow size fractions in the 25 x 0.8 mm size range. The -0.8 mm fraction is screened out ahead of the jig plant and rejected as waste without any prior beneficiation. The processing of this fraction was not included in the early stages of SEP development because no suitable beneficiation or dewatering technologies could be identified within the time-frame required to implement SEP. This paper presents the SEP 1B project, ie the metallurgical and process engineering study that was done to evaluate the techno-economic viability of processing the -0.8 mm material of SEP. To support this evaluation, metallurgical bench scale testwork was done on selected samples characterising the material types used in the SEP for gravity concentration beneficiation. Subsequently, pilot testwork on a 300-ton bulk sample demonstrated that an integrated teeter-bed/spiral circuit could be used to successfully beneficiate the -0.8 mm fraction. The study has established the viability of the proposed process and has concluded that approximately 390 000 tpa could be produced and added to the SEP fine ore product without violating the applicable product specifications. The proposed process has been designed to be implemented in modular units in order to facilitate implementation and ensure future expandability. Based on the recommendations of the study, approval has been granted for the detail design feasibility study. Production is scheduled to commence in the first quarter of 2010.

Jan 1, 2008

By Vestre J, Kure K, Bergqvist I

Existing practical laboratory tests for comparative strength determination of commercial explosives consist of the lead block test, the ballistic mortar test, the bubble test etc. These tests are carried out in material with quite different properties compared to rock. The theoretical performance potentials of commercial explosives are traditionally described by weight-strength (WS). Some explosive producers use the Langefors formula for weight-strength calculation, where also the gas volume is considered. Neither the theoretical nor the practical methods for determination of explosive performance such as the above, give good enough prediction of fragmentation and heave in rock blasting. For these reasons a project was started for the purpose of finding a small scale test method which predicts how different explosive parameters affect fragmentation and heave. Small scale tests were carried out by using 50 cm cubical blocks, mainly of concrete, but a few also of rock. All blocks were blasted in a steel cylinder with a diameter of 1.2 meters. The velocity of detonation was monitored, and the velocity of fragments was derived from their time of arrival at the steel wall, which was registered by accelerometers. After blasting all fragments were screened. The charge diameter was 22 mm and the amount of explosive 78 grammes, resulting in a specific charge of 0.62 kg/m3. Explosive properties such as energy, gas, VOD and density were systematically changed.The results presented in this paper show how fragmentation and heave systematically change when the explosive properties like energy, gas, VOD and density are systematically changed. The results from the small scale tests are compared to full scale tests carried out in tunnel blasting, and during summer 1990 also in bench blasting.

Jan 1, 1990

By B Cook, M Karakus, J Light, E K. Chanda

The aim of this research is to develop a model through which the appropriate paste recipe parameters, for example solid content and cement content, can be derived given the stope specific requirements such as stope dimensions, required strength and curing time. A large number of samples and uniaxial compressive strength (UCS) tests were conducted at the Angas Zinc Mine (AZM) paste plant and testing facility. Samples were varied in tailings solids content, cement content and sand content. The results of this testing were modelled to determine the UCS relationship to each of the parameters. The output of this modelling was an easy-to-use program that outputs the design mixture given the stope dimensions and required stope backfill-curing time. This allowed flexibility within the mining schedule for curing times of cemented paste backfill stopes. The optimised schedule using the stope specific mix design, when compared to the standard 14-day curing time used previously, resulted in a smoother weekly mine production schedule. For the modelled 12-week period (one quarter) the 14-day curing time would result in an eight-day shutdown of the mill. The cost for each shutdown is in the order of $125 000/d. Due to the unique nature of each mine’s tailings, this exact outcome would not be directly applicable to another paste fill site. However, the process in this report could be followed for another site to achieve a system similar to the output of this project. This would ultimately lead to a more optimised backfill and stoping cycle and a more optimised mine.CITATION:Chanda, E K, Karakus, M, Light, J, Cook, B and Harris, A, 2014. Optimisation of the paste fill cycle at Angas Zinc Mine, Strathalbyn, South Australia, in Proceedings 12th AusIMM Underground Operators’ Conference 2014 , pp 259–264 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 24, 2014

By M I. Pownceby

High temperature roasting studies on chrome-spinel contaminated ilmenite concentrates showed that sulfur, introduced through a sulfidising roast treatment, selectively reacted with the chromium in the spinels. The roast treatments were carried out in a laboratory scale rotating drum kiln using a standard Becher-style heating profile (10 h, 1075ºC), char as the reductant, and variable amounts of added elemental sulfur (0 - 3 wt per cent).After roasting, bronze-coloured grains were visible representing chrome-spinels that had undergone selective sulfidisation. SEM imaging of the products showed that sulfur was preferentially concentrated in ~5 - 15 µm thick rims fully enclosing the chrome-spinel grains. The sulfur-rich rims became a sink for manganese (Mn) from the ilmenite resulting in the rims being rich in Cr-Mn-Fe-sulfides. Quantitative electron probe microanalysis of phases present within the rims identified two sulfide phases. The first sulfur-phase (S-phase) was low in Mn (1 - 3 wt per cent) and high in Fe, Cr and S, while the second S-phase was considerably higher in Mn (30 - 35 wt per cent Mn) and lower in Fe and Cr. The dramatic change in the composition of the chrome spinels after sulfidisation is likely to significantly alter their physical properties (eg hydrophobicity, conductivity, etc). This should make their physical separation from the ilmenite potentially easier than roasting/magnetic separation methods.

Oct 5, 2011

In April, 1990 the Sydney Water Board invited bids for the construction of the Hazelbrook Carrier Section 3 being part of the Blue Mountains Sewerage Transfer Scheme. In December 1990 the contract was awarded to Costain Resources Limited, Mining Services Division for the sum of $A15.3 M. The works consisted of excavation of 9 520 linear metres of tunnel, 3.35 metres diameter with installation of permanent ground support in the form of rockbolts, mesh, steel sets, shotcrete and in situ concrete

Jan 1, 1993

This is a brief introduction of a sewer pipeline constructed with a pipe jacking method in combination with a 1 200 mm finished inner diameter tunnel boring machine developed for the first time in Japan. The pipeline is located under a national highway running through a densely built urban area and is 185.7 m long and 2.9 m to 3.7 m deep from the ground surface. The geological features along the pipeline show mostly slate and partly silt. The pipeline was constructed with a newly developed multi-application type tunnel boring machine equiped with a fluid transport system. The construction consisted of tunneling by a tunnel boring machine followed by pipe jacking operations. The excavated materials were dis- charged off the tunnel by a fluid transport System.

Jan 1, 1987

By R Castedo, P Segarra, I del Castillo, L M. López, J A. Sanchidrián

This work investigates some suggested methods for blast vibration monitoring on a hard surface based on 53 tests on a vibration exciter. Errors in the measurement attributable to coupling have been described as function of frequency by the rock-to-mount (or coupling) transmissibility, ie ratio of the velocity of the vibration sensor mount to the velocity of the rock motion. Transmissibility has been measured from 2 to 200 Hz, at two vibration levels (5 and 20 mm/s), in four seismographs. Attachment methods with an anchor, thermal adhesive and gypsum plaster allow stiff rock-to-mount coupling. They ensure accurate measurements (errors below 0.3 dB) for frequencies commonly found in blasting (below 100 Hz) irrespective of the mount characteristics and the vibration level. Free laid mounts and sandbagged vibration sensors lead generally to a poor, weak coupling. Errors are non-linear errors with the input velocity, ie the operating frequency window narrows as the velocity of the ground increases. Free mounts follow ground motion acceptably well (error up to 0.4 dB) at both vibration levels and frequencies below 15 Hz. At higher frequencies, free mounts lead to the largest distortions with expected errors ranging from 0.8 to 6.6 dB. Sandbagging limits the expected errors below 1.3 dB, but it does not prevent large errors that can be up to 4.5 dB. Both frequency and velocity should be considered together to assess the measurement errors instead of the expected accelerations, as it is currently made.CITATION:Segarra, P, Sanchidrián, J A, Castedo, R, López, L M and del Castillo, I, 2015. Effect of vibration sensor mounting method on the quality of vibration measurements, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 545–552 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By A Duran

When dealing with rocks in the geotechnical profession, a common activity involves providing an estimate of the intact strength. The tactile approach and descriptions of strength that apply to soils is well documented, can be readily checked through the use of a pocket penetrometer and are known to provide reliable estimates of strength. Moreover, although different soil strength classification systems are present, the bounds between classification classes are compatible across almost all documented classification systems. However, this is not the case for rock strength materials. There are numerous systems within the literature, some with different concepts, and almost all have different bounds to each strength classification. In this paper, the author presents seven classification systems for estimating intact rock strength and highlights issues in their implementation. Example cases are presented to discuss the typical concerns confronting field strength estimates.CITATION:Duran, A, 2014. Comparison of field estimated strengths, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 101–106 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014

By H Park, L Wang

Froth flotation is one of the most widely used beneficiation processes for fine and ultrafine coals and minerals. Maintaining optimal metallurgical performance in industrial flotation operation is still a challenging task owing to the lack of an effective tool to diagnose the flotation performance in realtime. For this purpose, a number of flotation performance monitoring systems with different working principles have been developed to provide instant feedback for process control and optimisation. In this paper, for the first time, five different flotation performance monitoring systems were systematically compared through an on-site trial in a coking coal flotation plant in Queensland, Australia. The monitoring systems were used to measure (i) gas holdup, (ii) overflowing froth velocity, (iii) overflowing froth height, (iv) air recovery and (v) drag force exerted by overflowing froth, in an industrial flotation column and the outputs of these systems were collected simultaneously at a wide range of operating conditions. For each monitoring system, the best regression model describing the correlation between the system output and the flotation performance was selected from various regression models (eg linear, quadratic, power-law and logarithmic) using the Akaike information criterion (AIC). A comparison of the coefficient of determination (R2 ), residual sum of squares (RSS) and measuring accuracy at 95 per cent confidence level of the best regression models of these monitoring systems suggested that the drag sensor outperformed the other systems at a wide range of flotation operating conditions. The superior performance of the drag sensor was attributed to its distinctive design that enabled intimate sensing of variation of the overflowing froth properties. Furthermore, the drag sensor had the ability to monitor feed ash content variation when the other operation variables were set almost constant.

Aug 24, 2022

The purpose of this paper is to list by tabulation and flow sheet, the operating equipment and installations in use at Rosebery, and to refer to particular items which may be of interest for purposes of comparison, or because they possess some unusual feature. The general perspective has been taken from the viewpoint of operating and maintenance experience.The sequence begins with ore breaking and transport and proceeds through milling operations. The paper is in two sections, first, mechanical equipment, second, electrical equipment. A brief outline of a scheme for using gravel wash for stope filling, which is in course of installation, has also been given.

Jan 1, 1949

The weathering profile, in arid terrains, is commonly capped by different kinds of hardened crust, whose formation is related to recent or former climates. One may distinguish silcretes, calcretes and the ferruginous (or ferro-aluminous) laterites. the present keynote address mostly deals with the lateritic regolith and, moreover, the influence it has on mineral exploration. The lateritic regolith, also called "cuirasse", is a result of a massive accumulation of Fe (and/or Al) oxides on top of weathering profiles developed during former, probably seasonal humid, climatic episodes, and whose preservation depends on the characteristics of later climates. The total thickness of such weathering profiles commonly exceeds 50 m, with an almost complete substitution of the rock forming minerals by secondary minerals as kaolinite and Fe-Al oxi- hydroxides (hematite, goethite, boehmite, gibbsite). Such an alteration of the primary minerals assemblage is of course accompanied by significant changes of the chemical composition, as concerns major and trace elements. The latter are distributed amongst the main secondary mineral phases or trapped in some primary resistant minerals, but may also be leached, totally or partially. Gold is also affected by lateritic weathering, as shown for instance by morphoscopic and geochemical studies of gold grains collected in the different horizons of the profile, which indicates some dissolution followed by reprecipitation.

Jan 1, 1988

By B W. Ham

The legacy of underground coal mining may be a land surface which, in parts, may be unstable in the long term. A case study analysis has been undertaken to explain some of the hazards and how the risk may be assessed and managed.The Ipswich Coal Measures were extensively mined with shallow underground workings, which now underlie a number of suburbs in the eastern side of the city of Ipswich in south eastern Queensland. The area was subject to underground mining from the 1840s to 1997. In general, the mines were small, family-owned operations that were restricted by complex geology, interactions with neighbouring operations and ownership of surface facilities. The oldest available mine plans date back to the late 1890s.The residents in these mining areas have a long history of unexpected mining subsidence events. A level of risk management for property owners has been implemented by the Ipswich City Council, which requires a mining subsidence risk assessment to be submitted as part of building applications for property development in the areas suspected of having mining subsidence risk. This discussion examines a series of generic subsidence events and how the risk may be assessed and managed and the hazard controlled.CITATION:Ham, B?W, 2014. The legacy of underground coal mining – mine subsidence: Ipswich coal measures case study, in Proceedings Life-of-Mine 2014 , pp 113–120 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 16, 2014

By M Lee, J F. Carswell, G Reitsema

"The increased costs of underground mining have continually challenged engineers to identify opportunities for alternatives to common approaches to underground development. Considerations to the design of horizontal and vertical development at the Dugald River mine targeted inclined raise boring to reduce horizontal development, not only to reduce cost, but to allow development activities to focus on other areas of the mine.The mine plan consists of 50 raise bored ventilation shafts, of which 17 have been mined to date with diameters ranging from 3.1 m to 5 m and lengths from 30 m to 200 m. The expected performance and stability of these shafts has been determined using methodologies proposed by McCracken and Stacey (1989) and further refined by Peck, Coombes and Lee (2011). Actual raise performances have been collated and compared to a database of raise bore performances across Australia as presented by Coombes, Lee and Peck (2011), and form a database of raise bore performance specific to Dugald River.Opportunities to further optimise the mine plan and reduce costs have seen the introduction of large diameter-inclined raise bored ventilation shafts to minimise the required lateral development to connect the ventilation circuits. Large diameter inclined shafts ranging between 3.1 m and 4.5 m in diameter have been successfully mined with dips down to 70°, reducing the cost of lateral development by more than $1 million over the next two years.Both technical and operational challenges were overcome in the mining of large diameter-inclined raise bores, including modification of: existing methodologies of assessing shaft wall stability for inclined raises. These included variations of the McCracken and Stacey method and the utilisation of the modified stability number (N’) previously developed for stope performance (Potvin, 1988). both the collar and toe development profiles, including the general set-up of the raise bore drill rig to reduce the operational risks associated with angled raises.Due to their success, inclined raises have been designed for subsequent stages of the life-of-mine ventilation system at Dugald River. This has resulted in significant capital cost savings for the mine.CITATION:Carswell, J F, Reitsema, G and Lee, M, 2017. Vertical and inclined raise bore performance at Dugald River mine, in Proceedings 13th AusIMM Underground Operators’ Conference 2017, pp 313–320 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 16, 2017

By Stevenson I, Dickinson W, Taylor R. N

Despite flash smelting's widespread use little is known about the actual processes taking place in flash furnace shafts and comparatively few reports of sampling campaigns have appeared in the published literature. his paper reviews the previous reports of the use of horizontal trough samplers and analyses their expected collection efficiency. In the light of the deficiencies revealed by this analysis an isokinetic sampler was produced and a vertical sampling technique was also developed to obtain samples from directly below the burners in the shaft of the flash furnace at the Kalgoorlie nickel smelter. Comparison of the sizing of the samples obtained with the horizontal trough and isokinetic samplers confirmed the theoretical analyses and showed that the trough samplers were not collecting the fine particles. Besides providing data to validate mathematical models of the burners and shaft, chemical analyses of the shaft samples showed that the coal in the charge was reacting preferentially and that the plume of at least one of the burners was being deflected from its axial position. In the region directly below the burner there was evidence that the disperser on the burner was imparting more momentum to the coarser particles and that these were concentrating in the outer regions of the particle plumes issuing from the burners.

Jan 1, 1992