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By S Paciornik, G Schinazi, M H. de Pinho Maur-cio, M B. Vieira, O da Fonseca Martins Gomes, D T. Wagner

Vale (previously CVRD û Companhia Vale do Rio Doce) evaluates the microstructure of sinters in order to understand their characteristics and behaviour in the agglomeration process, and the correlation with conventional quality parameters. Efforts on image analysis development are in progress between Vale and PUC-Rio in order to improve both the qualitative and quantitative evaluation of a representative portion of material. In the present work, digital microscopy techniques were developed allowing this kind of assessment. Employing a motorised and computer controlled optical microscope, low magnification mosaic images covering complete sinter samples were automatically obtained. The mosaics provide a powerful qualitative overview of the whole sample while allowing low resolution quantitative evaluation of the major phases. In addition, quantitative results for phase fractions were compared for the same sample regions at three magnifications (5x, 10x and 20x objective lenses). A single field (1 x 1) at the lowest magnification corresponds to mosaics of 2 x 2 and 4 x 4 images at the higher magnifications. The automated system allows perfect registration between the mosaics and the single image. Changes in phase discrimination were evaluated as a function of optical resolution, and phase fractions obtained by interactive segmentation of the image histograms were compared. While finer dark phases, eg silicates, were only visible with the best optical resolution, coarser phases such as haematite and pores were measured at all resolutions. For haematite, magnetite, ferrite and pores, the largest relative error in area fraction, between the images obtained with the 5x and 20x lenses, was 12 per cent. The results for silicate were less accurate with a relative error of 44 per cent. The results indicate that digital microscopy provides a flexible method for qualitative and quantitative evaluation of these materials.

Jan 1, 2008

By Wright J. K

In recent years the production of steel from directly reduced iron ore pellets has ex- panded rapidly. However continued growth will depend on an adequate supply of suitable raw materials for the various commercial gaseous and solid reductant processes now in operation. Al- though at present Australia does not produce pellets primarily for direct reduction, there is an increasing awareness of Australia's potential role as a supplier of high grade ores for export and/or domestic use. The properties and quality requirements of iron ore pellets made specifically for directre- duction (DR) are reviewed and the laboratory techniques and test methods used at the CSIRO Division of Process Technology for the evaluat- ion of potential DR feedstocks are described. At the present time most of the evaluation tests for DR pellets are extensions of those de- signed for existing blast furnace (BF) burdens. In the case of some physical parameters such as cold compression strength, abrasion index and cold strength after reduction this extension is quite satisfactory. In the measurement of para- meters such as reducibility, swelling and stick- ing tendency, however, it is necessary to deve- lop meaningful standardized tests so that ores and pellets can be ranked for DR performance. To do this, data from the laboratory tests and from operating plants must be correlated.

Jan 1, 1980

UNLIKE coal mines, in which some form of artificial ventilation is rendered necessary by gases given off by the material mined and is also enforced by the mining laws of all countries, metalliferous mines have almost entirely relied on natural ventilation, viz., that due to the difference in temperature between the outside atmosphere and the mine air. In small mines natural ventilation has proved sufficient, but as mining proceeds at a greater depth, and where large ore bodies arebeing attacked the writer is of opinion that some means of artificial ventilation will be rendered necessary if only from an economic standpoint.The Broken Hill Proprietary Mine was one of the first metal mines to introduce a scheme of artificial ventilation on a large scale. In order to render the working conditions of the semi-friable stopes of Block 12 and the lower levels of Block 11 morecomfortable for the men at work in these places, in 1903 it was decided to install a fan to thoroughly ventilate these stopes. The fan chosen was a Capell double-inlet fan beltdriven from a steam engine: this engine was later on replacedby an electric motor. The fan was put in commission at the latter end of 1904; its principal dimensions are as follows: Length 6 ft. 6 in., diam. 7 ft., diam. of inlet 4 ft. 7i in. The fan is reversible, though this is a rather misleading term, asthe direction in which the fan blades revolve is not reversed...

Jan 1, 1921

By Purvis A. H, Greenwood-Smith R, Sowerby B. D

A nuclear technique for the determination of copper and nickel in bulk samples and drill core has been developed at Lucas Heights andfield-tested at Mount Isa. The technique, which is highly specific to the element being measured, utilises the gamma-ray resonance scallering process.A bulk mineral analyser was installed in mid-1976 for the routine assay of copper in bulk samples and drill cores, and remained in operation until late 1981. The operation of the analyser over this five-year period is reviewed with particular emphasis on reliability, accuracy and principal usage.The main application of this analyser was in stope planning and design whereby several thousand drill-core and Wall-chip samples were analysed. It was also used as an aid to underground grade control of stopes where ore dilution by supporting barren backfill was a problem.

Jan 1, 1984

By Peng S. S

Measurement of pressure distribution under the base plate of the Hemscheidt 2-leg 800-ton shield was performed underground for two shifts using 12 pressure cells installed in two rows, one each under each split base plate. Pressure distribution was uneven depending on contact condition. In general the highest base pressure occurred at 1/3 of the base plate contact length from the rear edge. The resultant was near vertical, and the pressure under the tail side split base plate was always higher than the head side. For comparison, pressure distribution on the canopy and under the base plate was also measured under controlled conditions at the USBM's Mine Simulator Testing Facilities in Pittsburgh, PA. A total of 45 tests were conducted under several simulated contact conditions. The results showed that the actual contact area is highly dependent on the compliance of the immediate roof and floor due to the sloped canopy tip and a base lifting device under the base tip. The loading distribution tends to change in magnitude and profile as the leg pressure increases. The base lifting device exaggerates the high toe loading on the base plate characteristics of this type of shield support.

Jan 1, 1992

Over the last 15 years working in the mining, construction and extractive industries, one of the areas that has always concerned and at the same time drawn the author to it is the application of drilling and blasting in the underground development mining and civil construction tunnelling fields. In that time, the author has come across many drives and tunnels that are larger than design or badly damaged in the perimeter or both. When the question is asked as to why this is the case, the reply is generally æthatÆs the way it is and always has beenÆ. Sometimes it is blamed on bad ground, bad drilling, bad explosives, bad initiation or just plain bad. Most operators build a dilution factor into development and tunneling costs as an acceptance of overbreak and similarly pattern bolt everything to overcome excessive perimeter damage. This paper will attempt to unravel some of the mysteries behind perimeter drilling and blasting in underground drives and tunnels and discuss methods to reduce overbreak and therefore reduce costly dilution and to minimise perimeter damage which in turn will allow more cost-effective ground support. It should not be assumed that better drilling and blasting alone would automatically allow an operation to reduce ground support. The operator must still æreadÆ the ground and its characteristics in order to ensure sufficient ground support is placed to allow the operation to progress safely. This paper will not go into the intricacies of bolting, meshing, shotcreting, concreting and other ground support, but it will use indicative costs for the primary areas of drilling, explosives, excavation and labor to show the magnitude of cost-efficiencies which can be obtained through improved drilling and blasting applications. Drill and blast remains the most flexible and cost-effective method of underground excavation as long as it is applied safely and effectively.

Jan 1, 1999

By P Kappen, R N. Collins, K M. Spiers

X-ray absorption spectroscopy (XAS) is a synchrotron-only technique used to determine chemical speciation, providing a powerful alternative to most traditional ‘wet chemistry’ and lab-based speciation methods. XAS is an element specific method that can be used to address a variety of systems, ranging from heterogeneous to homogeneous, polycrystalline to amorphous, and solid to liquid. The strength of XAS in identifying and managing chemical species in tailings and mine waste is demonstrated, with the presentation of highly relevant studies into lead, uranium, chromium and arsenic speciation. In each example, waste samples are compared with known standards, allowing an assessment to be made of the quantity of particular chemical species in each.CITATION:Spiers, K M, Collins, R N and Kappen, P, 2015. ‘Forget the wet chemistry’ – how the Australian Synchrotron can help with tailings and mine waste management, in Proceedings Tailings and Mine Waste Management for the 21st Century , pp 145–148 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 27, 2015

By S Planeta

The use of explosives in underground mining has its drawbacks, particularly in the case of thin or narrow vein type deposits. Due to that, there is a need to develop more discriminative and safe rock-breaking technologies. Mechanical rock splitting seems to be one of the most promising avenues in this respect. This paper describes briefly principles and features of radial-axial splitters. It reviews a feasibility study done to evaluate a potential of this technology in selective mining. It was intended to compare productivity and cost of ædrill-splitÆ mining with conventional cut-and-fill method. Hypotheses and assumptions adopted, methodology used and the obtained results are presented and discussed. The study has confirmed an interesting potential of radial-axial splitters in mining thin and narrow vein deposits. In conclusion, it is stressed however, that it will take more R&D work to corroborate the results obtained. Some suggestions concerning future research in this field are also given.

Jan 1, 2003

By D R. Chalmers

Coal dust explosions have occurred in coal mines across the world. The Mitsui Miike Coal Mine disaster in 1963 was an example of how this hazard was not managed effectively, resulting in the loss of 458 lives and hundreds of people sustaining permanent brain injury from carbon monoxide poisoning. Management of the risks for this hazard have been well documented and have been implemented in modern coal mines. A recent trend in some mines has seen the abolition of barriers on roadways on the basis that the risks are being managed by the current controls. These controls include stone dust application, trickle dusters, dust analysis and dust removal. This paper explores the science behind such controls and questions the need for barrier protection on belt roads.CITATION:Chalmers, D R, 2013. Cybulski revisited - Lessons on dust, in Proceedings The Australian Mine Ventilation Conference , pp 165-168 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 1, 2013

By S C. Dominy

The Minerals Education Australia program is offering a tertiary learning environment for the global mining industry. The Minerals Council of Australia has instigated this initiative, which is run by the Minerals Tertiary Education Council. The program is a pioneering partnership between the Australian minerals industry, Australian governments and key Australian universities. It is designed to deliver key undergraduate and postgraduate courses for tomorrowÆs minerals industry professionals in the fields of geoscience, mining and minerals engineering and metallurgy. The flagship course for geoscience professionals is the G3 Masters program. This is a coursework-based degree supported by the Minerals Tertiary Education Council, and a partnership between James Cook University, the University of Tasmania and the University of Western Australia. These partners represent the leading-edge providers of minerals geoscience education and R&D in Australia. The G3 program provides the full spectrum of post-graduate training skills in exploration, mining and economic geology topics.

Jan 1, 2003

By R Kahnt, S Jahn, D Baacke, M Eckart

Relocation into the Lichtenberg open pit mine of about 110 million m3 of sulfide-bearing and ARD-generating waste rock piled up on the surface is the most important and cost-intensive single surface restoration project conducted by WISMUT GmbH at the former Ronneburg uranium mining site. The waste rock comprises for the most part Palaeozoic shales, limestones and diabases with pyrite contents of up to seven per cent. Waste pile relocation began in 1992 and is scheduled to be completed by 2007. The approach used for relocation has been extensively described elsewhere (Jakubick et al, 1997; Hockley et al, 1997; Chapman et al, 1998; Paul, 2003). Following completion of the backfill that will be up to 60 m above the initial ground level, a dry cover will be placed on top of the backfilled mine wastes. The area to be covered amounts to about 220 ha. Design planning for the final cover placement of which is to begin in 2004 had to be based on a comprehensive cost-benefit analysis over and above compliance with legal requirements. The crucial question to be answered in this respect was to determine û in addition to the expenditure required to ensure reuse, radiation protection and soil protection û the extent to which additional time, effort and money were justified in order to minimise contaminant release from the unsaturated portion of the backfilled pit contributing to total releases into the ground water and possibly achieve savings in long-term operating costs for the on-site water treatment plant. Optimisation was based on contaminant balance modelling for the entire site reproducing dominant physical and geochemical processes. Among the specifics underlying the cover design is that contaminant release from the backfilled open pit must not be considered independently of that from the adjacent flooded underground mine and that a major part of the backfilled open pit will also be submerged. Following weighing of cover-related short- and long-term costs it was found that higher construction costs for the various cover options will not be offset by cost savings in the long-term water treatment. As a consequence of pit flooding, even a costly multiple cover including an impermeable layer will only insignificantly impact on concentrations and loads at ground water spill over points. As a result of comprehensive studies and investigations, a combined cover of cohesive soil material from on-site excavation overlain by a 0.4 m thick storage layer to restore natural soil functions for revegetation was derived and submitted for approval. Together with hydraulic measures, this approach is to meet any requirement in terms of radiology, water protection, stability, erosion protection, and reuse.

Jan 1, 2003

By D G. Miljak, J Khachan, B K. Schwitter

The performance of prototype magnetic resonance sensors suited to mineral measurement in conveyor, slurry or portable applications is described. The sensors can be positioned around conveyors and modified slurry pipes, providing deep penetration of the sensing field, relative insensitivity to ore surface conditions and high mineral discrimination. Measurements on slurry, concentrates and ores sourced from mine operations are presented for two applications. Firstly, the quantitative measurement of chalcopyrite in slurry was demonstrated in laboratory measurements. In a calibration test, a standard error of 0.1 wt per cent and detection limit of 0.3 wt per cent was obtained. Secondly, results were obtained for the discrimination of iron ore texture. Signals were readily observed using measurement integration times of seconds to several minutes, depending on ore material. The results demonstrate the feasibility of online quantitative analysis of selected minerals in processing applications using magnetic resonance.

Jan 1, 2008

One of the major changes in the resource industry in the nineties has been the re-internationalisation of the industry. The history of the resource business has been one of companies from the developed world utilising the cash flows from their operations to explore and develop mines in less developed regions of the world. This resource development has progressively generated wealth and economic development, which in turn, has led to a new generation of exploration and mining projects. In South America, Chile had led the way in a mining resurgence, now closely followed by Argentina, Brazil, Venezuela and Peru. Although Chile has long had a significant copper mining industry, the pre-nationalisation phase was driven by American capital; the current phase has been spearheaded by R.T.Z. - B.H.P. at Escondida with Canadian junior companies, in particular, providing major speculative impetus. The Australian junior companies have not been significant in South America.

Jan 1, 1995

By Li YQ, Yoon RH

The photoresponse of natural mineral pyrite and galena electrodes has been studied in aqueous solutions on freshly fractured surfaces (some fractured in situ) using moderate overvoltages. When fractured in situ, the electrode potential of both minerals instantly drops several tenths of a volt. Pyrite exhibits a spontaneous anodic photocurrent at fracture, which indicates upward band bending (depletion layer) on the n-type electrodes. The negative surface charge responsible for the depletion layer is believed to arise from a surface state that is intrinsic to pyrite surfaces, possibly modified by hydroxide ion adsorption. The flat band potential, Vty, of pyrite is at approximately -1.0 V (SCE) at pH 9.2 but to reach V(b, pyrite has to be cathodically decomposed. In contrast, galena assumes the flat band potential at fracture. Subsequent polarisation of galena at potentials positive of Vth produces an anodic photocurrent (upward band bending) and polarisation negative of Vro a cathodic photocurrent. Most of the galena electrodes studied were degenerate n-type and at potentials negative of Vtb, no cathodic photocurrents are observed, indicating the bands cannot be bent downward, consistent with the Fermi level at the surface merging with the conduction band edge near Vn,. Several were close to intrinsic, with the photocurrent changing sign near Vn,.

Jan 1, 1993

By P Audet, D R. Mulligan, D Doley

This analysis attempts to reconcile existing ecological theories, rehabilitation planning goals and implementation constraints in the form of a rehabilitation paradigm that considers potential and pragmatic ecosystem transformation pathways. The framework prioritises multiple developmental scenarios for post-disturbed landscapes within a continuum of ecological outcomes. A feature of the framework is that ænovelÆ ecosystems and agro-ecosystems, having a range of commercial and societal values, are valid outcomes spanning the conceptual divide between the ecological functions of under-rehabilitated versus re-instated ænaturalÆ landscapes, especially in a changing environment. Landscape suitability analyses are considered to be fundamental to the incorporation of regional landscape and climate in the implementation of land rehabilitation and management strategies. Altogether, the paradigm could facilitate the identification of widely pertinent rehabilitation goals having direct implications at the regional scale of restoration ecology and acceptance of the need for ongoing commitment to the management of disturbed environments.CITATION:Audet, P, Doley, D and Mulligan, D R, 2012. Can ænovelÆ ecosystems offer suitable rehabilitation alternatives for post-mined landscapes?, in Proceedings Life-of-Mine 2012 , pp 135-142 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 10, 2012

By F Sandrone, J-P Dudt, J Zhao, E Paltrinieri

Tunnel boring machines (TBMs) excavation is nowadays more and more considered a valuable alternative to conventional tunnelling. As a matter of fact, thanks to its advantages such as greater rate of advance and safer working conditions, the application of TBMs has increased significantly in recent years. Despite the possible excellent performance of TBMs in favourable ground conditions, the advance rates could be significantly slowed down or even obstructed in limiting geological situations. This obviously traduces in potentially longer tunnel construction times and higher costs and, therefore, in a preference for conventional method. One of the major geological hazards encountered during tunnel construction, is related to the presence of fault zones or heavily jointed and fractured rocks. The most common geotechnical problems resulting from tunnelling in these difficult conditions include the instability of the excavation face, instabilities of side-walls producing large overbreaks on the tunnel profile, excessive deformations in case of squeezing grounds, frequently changing stresses in terms of magnitude and direction, high water inflows, etc. The decisions aids for tunnelling (DAT) is a model and a computer code that can be used to evaluate the influence of the uncertainties related to both the geological/geotechnical conditions and the construction process on final tunnel construction time and costs. In this framework, the DAT is used for assessing the effects that challenging ground conditions may have on tunnelling operations in terms of costs and delays. This is done by simulating the tunnel construction considering several geological profiles. The aim of the study is comparing different excavation methods (ie drill and blast versus TBM) in changing ground conditions along the tunnel alignment ranging from good rock, to very poor and fractured formations. The results show the impact, in terms of changing construction time and cost, of the excavation method versus the ground conditions.CITATION:Paltrinieri, E, Dudt, J-P, Sandrone, F and Zhao, J, 2014. Comparison of excavation methods in different ground conditions with the decision aids for tunnelling, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 573–580 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

Like almost any other 19th century mining area, the West Coast saw its 20th century scrapping era when machinery which had been installed in seemingly inaccessible places was somehow dragged out again. Fortunately there were some spots so remote that they defied even the most zealous of these pioneering recyclers. One of these was Big River, a mining locality in a rugged landscape straddling the headwaters of the Grey and Inangahua rivers. As a result there remains an internationally important collection of mining equipment including a poppet head, two steam winding engines, a pair of boilers, part of an aerial cableway with its loading system, and remnants of a stamp battery along with its associated gold smelter, cyanide tanks and zinc boxes. There are also assorted building remains associated with 60 years of mining and settlement. Since their abandonment in 1942, these relics have all somehow survived a further half century in a far from favourable climate with two or three metres of rain a year, frequent snowfalls and hot summer temperatures. The rate of decay during the past few years has been alarming.

Jan 1, 1996

By M Simanjuntak, A M. Supomo

PT Freeport IndonesiaÆs copper/gold operation disposes of approximately 222 000 dry metric tonnes of tailings per day via two thickeners. Reduction of the flocculant dosage rates in each of the tailing thickeners has been achieved with the installation of Clarometers«, modifications to the existing operating DCS control strategy and a change in plant flocculant. This has reduced the flocculant consumption rate in the last twelve months by approximately 20 per cent. It has also highlighted the disparity in the settling rates of the two thickeners. Collaborative efforts between Cytec technical site engineers and Freeport operational personnel have made possible the overall gains achieved in the tailings thickener optimisation.

Jan 1, 2003

By C Tukel

Copper sulfate is traditionally used to activate various types of sulfide minerals. The list of users includes Falconbridge Sudbury operations, where copper sulfate solution is added to the pyrrhotite/pentlandite middlings at the scavenging stage. Results from some batch tests reported in the literature suggested that copper activation is helpful for the improvement of pentlandite recovery, especially in the difficult to float fine particle range. Any improvement in pentlandite recovery is important since it is the main nickel bearing sulfide mineral. The impact of copper sulfate for this function has been investigated. Since the focus of current investigation was the flotation behaviour of minerals at the scavenger stage, rougher flotation was kept as constant as possible at two different weight recoveries, namely 13.2 per cent and 15.5 per cent that is relevant to industrial practice. Samples taken during batch testing were extracted using DETA and flotation products from selected tests were analysed to determine the recovery by size behaviour in relation to the use of copper sulfate. Results provide significant evidence that the addition of copper sulfate to these middlings does not yield greater nickel recovery, either on an overall or specific particle size basis. It is concluded that copper sulfate is wasted in the process and that self activation behaviour of the ore at a slightly reduced pH is sufficiently significant to maintain the scavenger recovery of pyrrhotite and pentlandite at desirable levels. Results obtained from limited circuit trials have shown supporting evidence for this conclusion.

Jan 1, 2005

By Mullens P

Recent advances in technology have allowed many of the problems of directional control of long diamond drill holes to be overcome. Three case histories are presented, from Cobar, Hilton North and Mount Isa Mine, in which careful hole design and the use of wedges and down-the-hole motors have allowed tight directional control of drilling. Substantial savings in time and cost were achieved in all three cases.

Jan 1, 1990