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By A Hocking, S Henderson

Commonwealth of Australia (2016) defines rehabilitation as comprising “the design and construction of landforms as well as the establishment of sustainable ecosystems or alternative vegetation, depending upon the desired post-operational land use”. For open cut coal mines in Queensland and New South Wales, the question of how to apply this intent to pits at mine closure is repeated for hundreds of individual pits. In EISs, closure plans and public discussion, assorted treatments are proposed to rehabilitate pits. While some aspects of final voids have been intensively studied, there is little guidance on how to choose a final void treatment option that delivers the optimal outcome against rehabilitation goals. For example, in the Bowen Basin and Hunter Valley commonly proposed rehabilitation actions include reducing the angles of pit walls; however, with few voids successfully rehabilitated to date there is limited understanding of what different wall slopes will achieve.CITATION:Henderson, S and Hocking, A, 2018. A decision framework for comparison of coal void rehabilitation options, in Proceedings Life-of-Mine 2018, pp 127–130 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 25, 2018

The tragedy of the Moura No. 2 incident has lost much of its emotional mileage for those organisations that thrive on loss and suffering. However, for the families, workers, mine owners and operators in the Queensland underground coalfields, the challenge of delivering a positive outcome, though well underway, is in its infancy. The pressure created by interested parties is necessary for overcoming the inertia involved in change; but they cannot deliver the change. The responsibility ultimately resides at each individual minesite with the people who work there each day.

Jan 1, 1998

Cable bolts have been used extensively in the development of the footwall of the Mt Whaleback Mine as a part of the ground improvement program since 1986. High tensile seven wire stress relieved steel strand similar to that used in pre-stressed concrete and grouted in place with sulphate resistant cement have been employed for rock-mass reinforcement.Most of the footwall is developed in Mt McRae Shale which contains a 20 m thick pyritic shale layer 14 m below the ore/waste contact. Due to extensive folding of the footwall rocks, the pyritic shale layer regularly occurs on, or close to the pit slope. Rain water run-off seeping through pyritic shale becomes acidic to the extent where its pH value can be as low as 1.5.

Jan 1, 1992

By Kavetsky A, Scott A

As well as breaking and moving rock, blast energy sets up a seismic wave in the ground which can cause significant damage to rock structures and buildings and disturbance to human occupants. This seismic ground vibration is potentially most damaging when its dominant frequency coincides with the resonant frequency of a structure, leading to high amplification factors between the input ground vibration and the resulting structural response. This paper outlines methods of identifying the resonant frequency of structures. It also describes a practical numerical method for the modification of blast designs to reduce the ground vibration energy in critical frequency ranges. The method is illustrated with two recent case studies.

Jan 1, 1990

By Dhawan AK

On 8 July 1993, a landslide of about one million cubic metres of rock blocked the river Satluj near Sanjay Vidyut Pariyojana - Bhaba project and caused flooding into the Bhaba Power House (120 MW) resulting in suspension of power generation. The concerned authorities desired an early removal of the blockade by an underwater blasting operation into the over topping water to reduce the water level at the blockade and resume power generation in the power house. In the absence of underwater drilling, it was essential for the blasting technique to be used where no cavity to confine the explosive was required. For this reason mud capping and plaster shooting with directional throw were used and additional specially fabricated mild steel pipe charges were used under high current for an underwater trenching operation. By employing these techniques the river blockade was removed up to the required depth and on 8 September 1993 the Power House resumed the power generation.

Jan 1, 1995

By B, G Strobos, J P. Maree, N Smit

In mining and processing operations where minerals, high in pyrite and low in calcite/dolomite are processed, acid is generated, which needs to be neutralised. Ticor at Empangeni in South Africa (SA) produces rutile (TiO2), leucoxene (TiO2 plus iron compounds), titanium (Ti), zircon (Zi) and ilmenite (TiO2 plus iron compounds). Neutralisation is required in the processing plant where acid is leached into the wash water. This water needs to be treated to a quality suitable for re-use in the metallurgical process or to a higher quality to make it suitable for discharge into the Empangeni sewage system (SA). For re-use the water needs to be neutral and under-saturated with respect to gypsum while for discharge into the sewage system the sulfate concentration needs to be reduced to less than 500 mg/L (as SO4). Acid mine water is generally neutralised with lime. Disadvantages associated with lime are the costs and maintenance of the slaking equipment as well as hazards, associated with handling of the alkali. The cost of powdered limestone (CaCO3) in South Africa, a by-product, is 50 - 60 per cent cheaper than lime. A technology has been developed where limestone is used for neutralisation of acid mine water instead of lime. This development includes: Limestone handling and dosing system. A novel, robust system has been developed where waste CaCO3 from the paper industry is slurried to a constant density. A full-scale plant was constructed to evaluate its performance (Figure 4). The dosing system consists of an inclined slab onto which the limestone is stored and from where it is slurried into a make-up tank. The density of the slurry in the make-up tank is controlled via a loadcell that measures the weight of the tank (operated at constant volume) and activates/deactivates the spray of the recycle slurry onto the slab. Integrated limestone neutralisation/lime treatment process. In this process powdered CaCO3 is used for neutralisation and partial sulfate removal of acid leached from the coal washing plant. The sulfate concentration can be further reduced to below the saturation level of gypsum (ie 1200 mg/L) through gypsum crystallisation by means of lime treatment, resulting in metal precipitation (eg Fe3+ and Al3+). CO2- treatment for CaCO3 precipitation. The pH of the lime treated water can be adjusted to pH levels of 8.5 and lower using CO2. The CO2, generated during limestone neutralisation (Equation 2), can be captured and used in this stage of the process. The first two stages (limestone- and lime neutralisation) of this technology have been implemented on full-scale at Ticor to treat the effluent of the process. The constructed plant is 80 m3/hr and differs from coal processing plants by way of not containing Fe(II) and Fe(III) in the water. The CO2-treatment stage (Stage 3) will soon be implemented at IHM as part of a program to optimise the technology for maximum benefits.

Jan 1, 2003

By M Roche, W J. Huxley

Finding a balance between practical and acceptable groundwater management, and providing for the needs and impacts of mining developments remains a challenge. The changes that accompanied the recent implementation of water reforms have provided greater flexibility for the water manager and greater certainty for the resource user. However uncertainty associated with understanding of complex aquifer systems, balanced against providing for the needs of mining developments, the rights of existing water resource users and expectations of the broader community have not diminished the conflicting issues faced by water resource managers and resource developers. Licensing under the Water Act 2000 provides the regulatory link with the taking of water for water supply purposes or as a consequence of the mining activity. This paper outlines key elements of sustainable water resource management involving certainty of access to water and adaptive environmental management that are delivered through conditioning the water licences issued for the particular mining development. Implementation of this approach is illustrated through a case study involving the BHP Billiton Cannington Mine in North West Queensland.

Jan 1, 2003

By Kyle J. H, Misra V. N

The most recent development in gold processing is the increasing use of heap leaching for the extraction of gold from low grade ore, and old tailings dumps. The reason for this trend is mainly to do with economics. The advantage of heap leaching is the considerable saving in both capital and operating costs. However, not all ores are amenable to heap leaching. It is only applicable to well oxidized ores that have suitable permeability char- acteristics, and the gold recovery is poorer than by conventional process. In this study, an attempt has ben made to ascertain the heap leaching characteristics of Western Australian gold ores on the bench scale using multiple, appropriately sized leach columns. The influence of particle size, flow rate, column depth and leaching time on the rate of gold extraction was determined. The percolation rate of cyanide leaching solution was deter- mined with and without gypsum additions. Efforts were also made to minimise particle segregation, fines migration and solution channelling during leaching, so as to improve solution percolation, gold extraction rate and recovery.

Jan 1, 1991

By Dalmijn WL, Valk HJLvd

At the Faculty of Mining and Petroleum Engineering, the Department of Raw Materials Technology, a mathematical model has been developed to predict the porosity distribution in an uniform jig bed. If the porosity distribution in an uniform jig bed is known, it is possible to correlate this to the settling velocity of particles with a density different from the density of the bed grains and thus model the stratification in a jig. For measuring the porosity distribution in the jig bed a method has been developed based on light absorption techniques.

Jan 1, 1993

The Greymouth Coal field is situated on the West Coast of New Zealand's South Island and has been mined for coal for more than 120 years. The area covered in this paper is within the Rapahoe Sector of this field and contains >200 million tonnes of low ash, low sulphur, bituminous rank coal. Paper No 6, presented to the 19th Annual Conference of the New Zealand Branch of The Australasian Institute of Mining and Metallurgy in Christchurch in August 1985 by R G Bowman, explained 'A Geologist's View' of the 'Economic Potential of the Greymouth Coalfield', and describes previous geological assessments of the Rapahoe Sector.

Jan 1, 1989

By Aspinall T. O

This paper discusses the identification and assessment of risk for mining developments particularly for open pit mining. A distinction between sensitivity studies and risk analysis is developed, demonstrating the importance of geological and mining engineering judgement -as applied by experienced practitioners to the analysis and assessment of risk in such projects. Technical and financial risk analysis are discussed under: ò mineral resources and ore reserves; ò mining and processing methods; ò project construction; ò financing; and ò costs and commodity pricing predictions.

Jan 1, 1994

By N Hungerford, A Coote, S Doyle, D Henderson, F Della-Pasqua

A systematic, detailed airborne geophysical programme carried out in the Taupo Volcanic Region (TVR) in 2005 by Glass Earth NZ Ltd culminated in the identification of 21 epithermal gold targets. In this paper we present the follow up ground-truthing results from the first target drilled, Tahunaatara (TAH).   The Tahunaatara target was identified by means of a multi-disciplinary integrated approach (ôdata interventionö) that defined and ranked the target as being highly prospective for epithermal gold mineralisation. A follow-up ground resistivity survey over the target area revealed the presence of a ôresistorö buried beneath an extensive cover of recent volcaniclastic material. Geochemical soil sampling carried out in conjunction with the resistivity survey yielded anomalous gold values.   The host unit at TAH consists primarily of flow banded rhyolitic lavas, volcaniclastic deposits and tuffs of the Ohakuri Ignimbrite with small outcrops of silicified bedded breccias forming local topographic highs. Results from the first orientation drill hole show wide zones of intense silicification, clay alteration and mineralisation. Sulphide mineralisation is disseminated throughout the core in association with hydrothermal replacement and also occurs in association with quartz veins and infill in fractures (sulphide-only veinlets as opposed to quartz + sulphide veinlets). Textural evidence from drill core indicates that hydrothermal fluid flow was multi-staged with potential for multi-stage gold, and other elements. The presence of polymictic hydrothermal eruptive breccias indicates a hydrothermal vent system.   Alteration varies from argillic to silicic, with pervasive adularia and vuggy silicification also present. Chlorite is minor and associated with quartz, illitic clay and adularia. Assay results currently available confirm the presence of anomalous gold values in association with zones of vuggy silica deposition and intense silicification.

Jan 1, 2006

By Davey KJ

Complex sulphide ores are characterised by complex texture of the valuable minerals. Any assessment of the performance of differential flotation circuits treating such ore should include analysis of the effects of poor liberation of the valuable minerals. Selected samples were taken from balanced size by size surveys of the flotation section of a concentrator treating an ore body containing fine grained galena and sphalerite in a matrix of iron sulphides which is mostly pyrite. liberation measurements were made using the QEM*SEM system on four or seven size fractions. The measurements indicated that less than 40 per cent of the galena and less than 60 per cent of the sphalerite in the flotation feed was liberated. The final concentrates were largely composed of composites of valuable minerals and iron sulphide however there was a small but significant fraction of liberated iron sulphide. Using the sized mineral flows obtained from the original balances and the liberation measurements, a satisfactory liberation balance was obtained. This enabled the effect of liberation on the flotation performance to be examined; not only for the entire circuit but also in the rougher, scavenger and cleaning sections. In the zinc circuit the effect of a regrind mill could be assessed. Recovery of galena in the lead circuit was limited by the recovery of composite lead particles. Recovery of liberated galena exceeded 95 per cent in all size fractions while the recovery of composite galena exceeded 85 per cent below 38 ¦m but fell sharply above 38 ¦m. Examination of the behaviour of the liberated and composite galena in the various sections of the lead flotation circuit revealed high recoveries of both liberated and composite galena particles in the roughing and scavenging sections but very low recoveries in the final two cleaning stages. Similar trends to those observed in the lead circuit applied in the zinc circuit although the performance of the liberated sphalerite also fell off at sizes greater than 38 pm in this case. Thus the zinc recovery was limited by the flotation of both the liberated and the composite sphalerite. The effect of regrinding was to increase the recovery of sphalerite mainly by reducing the amounts of sphalerite in less liberated sizes rather than by increasing the liberation of the sphalerite within a given size Fraction.

Jan 1, 1993

By Eggins SM, Crawford AJ, Wallace ME, Falloon TJ

The Earth's Upper Mantle is dominantly peridotitic but in convergent margin regions, such as the S.W. Pacific, subduction of oceanic crust gives greater chemical and petrological diversity to upper mantle petrology and petrogenesis. Examination of currently active, Quaternary and Tertiary volcanism in the S.W. Pacific, particularly seeking information from ocean floor sampling to characterize the basement to island arcs and to investigate active spreading centres, consistently points to parental magmas of basaltic to picritic character. However, these parental magmas are chemically diverse and it is not possible to designate a characteristic 'island arc' or 'convergent margin' petrogenesis in the sense of a characteristic mantle source composition and a charactistic partial melting regime. In this respect, magma genesis at convergent margins contrasts with that at oceanic spreading centres. Our studies emphasize the importance of source peridotite ranging from 'fertile lherzolite' (i.e. compositions with 3-4% CaO, A12O3, 0.3-0.5% Na2O) to refractory harzburgite (

Jan 1, 1987

Over the past 5 years, Bougainville Copper Limited has undertaken a number of major plant expansions to the copper concen- trate production plant at Bougainville in the North Solomons Province of Papua New Guinea. These projects have scheduled three additional ball mills, three new banks of Outokumpu flotation cells, four additional tertiary screens, two additional tertiary crushers, and more recently four high capacity 24.5m dia. tailing thickeners. The value of the five separate projects totalled more than A$100 million. A requirement of commissioning and bringing on line of each of these projects has been to minimise both operational losses and copper concentrate production. The commissioning has been successfully implemented by detailed planning of the commissioning work in conjunction with the plant operation. Planning has been detailed for each man involved on an hourly basis, highlighting the work required on each commissioning task that is to be undertaken and the time expected to achieve activity Completion.

Jan 1, 1986

A device is described which is suitable for the automatic sampling of dust in dust laden flue gases. This device, called a Venturi Sampler, consists of two pipes each fitted with a suitably designed venturi.Both pipes are placed in the flue where one acts as an open-ended reference tube and the other as the actual sampling tube.The gas sampling rate is automatically controlled so as to maintain a zero differential pressure between pressure tappings in the two venturi throats. The venturies are so designed that under these conditions the gas velocity in the sampling pipe is always equal to the free gas velocity in the flue-that is isokinetfc sampling conditions are maintained.INTRODUCTIONThere is a constant need in industry for regular and accurate assessments of dust losses, both to assist in improving operating efficiencies in order to minimize losses, and to obtain accurate metallurgical balances. In many cases where sampling is carried out in dust laden gases, the existing sampling methods are both laborious and inaccurate, and often make no provision for changes in flue gas velocity while sampling is in progress.In the majority of cases where a measurement of dust losses in a stack or flue is required, a preliminary velocity survey is made with a pitot tube to establish the gas velocity at each of the points at which samples are to be taken. The sample of gas (and dust) is withdrawn through a tube connected via a flowmeter to an exhausting apparatus. Some means of removing the dust from the gas sample is placed in circuit ahead of the exhausting apparatus. This is often an alundum or paper thimble housed in a gas-tight container.The purpose of the flowmeter is to measure the actual flow of gas during sampling so that the sampling velocity at the inlet to the sampling tube may be calculated, and the flow corrected so that the sampling velocity will agree with...

Jan 1, 1959

Process control computers are finding ever increasing applications within the chemi-cal and mineral processing industries.To purchase a system which fulfils both the immediate and future needs of operating, technical and management groups, requires an appreciation of the capabilities of the system software and the constraints which apply to user development of application software. Early decisions are then required as to who will develop and maintain the software. Rules and conventions must be determined and adhered to if the end result is to be an orderly, well structured and properly documented system. Software development and maintenance represents a substantial, and often hidden, cost. Getting it right the first time will avoid either a major re-work, or having to live with a system which is extremely diffi-cult (at the worst, impossible) to trouble-shoot or modify.

Jan 1, 1985

The genesis of the Bulong Laterite Ni/Co deposit spans some 60 per cent of earth history: from development of the parent rocks in the Archaean to lateritic weathering in the Cainozoic. In a man's term, the discovery and evaluation history of the deposits has also been protracted and, at any given time, the perceived value of the deposits has depended upon the available technology and world markets.

Jan 1, 1996

IntroductionHistory of MineTopographyGeology of AreaGeneral DescriptionIgneous Rock TypesGranodioriteQuartz monzoniteApliteGranite porphyryMetasomatic ActionAlteration of monzonite/Alteration of apliteGeology of Ore BodyNature of OreZones of MetasomatismAssociated Fracture PlanesDistribution of Copper MineralisationNature of Copper VeinsQuartz-chalcopyrite veinsQuartz-calcite-chalcopyrite veinsEuhedral quartz veins/Non-euhedral quartz veinsStructures Accompanying Ore BodyApliteIntersecting lines of metasomatised monzoniteMetasomatised aplite

Jan 1, 1949

Interest in mineral sand mining in the south west corner of Western Australia began in the late 1940's and significant production commenced in 1956. Early land use conflicts arose because of conservation implications (Ludlow tuart forest), expanded to include post-mining rehabilitation requirements (the Wonnerup mine near Busselton) and today include some agricultural/mining disputes. These latter conflicts are largely caused by the need for mining companies to secure longer-term reserves. To date, deposits containing mineral valued at A$440 million have been sterilized and are unlikely to become available in the future. There is additional pressure being placed on presently available reserves and a pessimistic picture could be drawn, whereby the southwest mineral sands industry ceases to exist by the year 2010. However, sensible land use planning, the support of policticians and the community, and responsible attitudes towards compensation and rehabilitation could, in combination, see the industry maintain significant mineral output until the middle of the 21st century. Examples of deposits sterilized by adverse land use will be given.

Jan 1, 1986