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By A Bouazza, J Kodikara

In this study, 23 samples of leached ash (LA) were collected from an ash pond at Loy Yang Power Station and geotechnically characterised. The samples were collected at various depths and locations within the ash pond on two separate occasions in order to account for the full variability. The LA within the ash pond at Loy Yang Power Station (LYPS) was found to vary in texture from silt to sand, depending on the location from where the sample was collected. Samples collected near the ash pond inlet discharge point, for instance, contained more than 50 per cent sand sized particles and were subsequently classified under the Unified Soil Classification System (USCS) as silty sand (SM). Further downstream of the inlet discharge, the LA became progressively finer and was classified accordingly as elastic silt (MH) when the sand content became less than 50 per cent. Basic geotechnical testing revealed that the LA from Loy Yang Power Station was generally acceptable as a landfill cover material. The permeability of LA, however, was generally too high for prescriptive covers, (ie resistive covers that generally rely on the impervious nature of the material to control percolation). Alternative covers, generally rely on the store/release function of a capillary or monolithic barrier to prevent percolation into the landfill. Subsequently, a material that can maintain a high water storage capacity while at the same time, readily allow infiltration and evapotranspiration is required for an alternative cover. Sandy silt and silty sand are optimal soils for alternative covers, as they do not yield water to gravity forces, but do give up most of the water in their pores when subjected to high-matric suction (Kavazanjian, 2001). The effectiveness of alternative covers is ultimately assessed using computer models, such as UNSAT-H and HYDRUS-2D, to rigorously perform water balance calculations. Prior to using a computer model to determine the highest possible percolation in the worst climatic conditions, it is necessary to select the most appropriate materials. This paper suggests a method to screen available materials for use as an alternative cover material on the basis of the soil water characteristic curve (SWCC).

Jan 1, 2003

Following the `Poseidon boom' of the early-1970s, there was pressure for development of a national body of company law and for the introduction and development of legislation to regulate the securities industry, including the Stock Exchange, trading in securities and securities dealers and advisers.After 20 years, the Corporations Law emerged in effect as Commonwealth legislation implemented automatically by the States.

Jan 1, 1997

Interest in mining narrow, vein-type ones has increased world-wide during the last few years despite the fact that prices of metals have not risen in proportion as production costs of mining, such as labour and energy.In many mines, where narrow ones are mined, the mining technique and equipment used have been poorly mechanized. The mining methods have been cut-and-fill or shrinkage stoping. Pneumatic jack-legs have been used for drilling and slushers have been used for loading.The methods that have been used can be called the "first-generation" methods.Work has been very hard for miners. It has been dangerous and exhausting.Production volumes of mines, and a s a result of that, also profits have been low.

Jan 1, 1990

By S Marsters

Imerys Tableware New Zealand Limited has mining rights to four deposits of halloysite, which are located about 203 km north of Auckland, New Zealand. These primary deposits were formed by the hydrothermal alteration and weathering of rhyolite domes. Halloysite clay is currently being mined from two of these deposits and then processed for export markets. From humble beginnings in the mid 1950s, the Northland halloysite was processed initially for paper filler markets and then for higher value tableware and technical ceramic niche export markets. The paper will briefly cover the geology and processing of halloysite and then examine the history of New Zealand China Clays Limited, now Imerys Tableware New Zealand Limited and then look to its future as part of global industrial minerals company, Imerys.

Jan 1, 2002

By M D. Boscardin, P A. Roy

The North Shore Connector Project for the Port Authority of Allegheny County involves TBM tunnelling twin light rail tunnels through cohesive soils and rock under the Allegheny River and a narrow city street. Along the tunnel alignment are a listed historic building on shallow foundations as well as modern buildings on deep foundations; one major office block was actually constructed directly over the alignment during the latter phases of design process. This paper provides an overview of the general site conditions, tunnel design and the technical basis for excavation support and tunnelling decisions. Deformation limits, ground improvement, monitoring and mitigation plans are also discussed. Project construction has now commenced and a brief summary of progress to date is included in this paper; this will be updated for the presentation to be made in Melbourne.

Jan 1, 2008

By Yeliseyev AK, Shestakov AM

Comminution is the most power-intensive process in the technology for ferrous quartzite concentration. That is why improving comminution efficiency leads to the most appreciable economic effect on the concentration process. The trend towards reducing the lump size of crushed ore before charging the mill is considered to be of major importance in improving comminution efficiency. A considerable number of investigations have been performed in this direction. At the same time, a strong interest is also maintained in the increase of comminution efficiency due to optimisation of process taking place in the mill. Recently, investigations of the power intensity of the breaking process inside the mill have been carried out at the Krivoy Rog Mining Institute. It was ascertained that the routine conditions of comminution at a low mill ball charge ratio resulted in an unnecessarily high power consumption due to the force of impact of falling and milling bodies far exceeding the power required for comminution. For example, the power value for falling balls of 60 - 125 mm in diameter reaches 0.3 kNm, and the force and stress due to ball contact with the lining reaches 60 kN and 250 MPa respectively. These values exceed the force required for comminution by a factor of ten. Analysis of the mechanism of ore particle size reduction during comminution in the ball mill indicates that the size reduction is due to impact load, attrition load, and static load. The efficiency of size reduction is very low. During comminution in the ball mill, impact loads prevail and amount to 85 - 90 per cent of the total load. In this situation, not more than 10 - 15 per cent of destruction is due to attrition.

Jan 1, 1993

One of the most significant problems experienced in land reclamation work has been the tendency of earthmovers to over-compact the subsoils and topsoils. The need for extensive subsoil drainage, because of over-compaction, becomes a very expensive exercise and can be attributed to poor planning. The problem has been addressed both at the Waihi and Huntly open-cast mines through the use of low ground pressure machines in the placement of subsoils and contouring. The use of subsoilers working to contour to aerate the soils is essential to integrate both the sub and topsoils so that significant root growth and drainage is established. Waihi's rainfall (approximately 200 mm annually) and light soils create difficulties in preparing for the final seed bed. A noticeable factor in preparation of the growing medium was the reaction of the lime particularly in the subsoils (damp), from a lumpy, quite heavy texture to almost a seed-bed texture within a period of approximately 72 hours. Also the high incidence of stone and debris which was not apparent in the placement of subsoils meant the job became very labour intensive. This will be overcome with the importation of a machine from the USA. All of the rubber tyred tractors used on these projects are four wheel drive in the 6S-aOhp range which for weight distribution and the safety factors allows for good landscaping techniques. Good engineering practices should ensure that slopes of no more than 3:1 be designed, keeping in mind that the long term planning must allow for maintenance and stock management of restored land.  In the preparation of the final growing medium the equipment used included: Caterpillar 05 LPG and blade; three-four wheel drive rubber tyre tractors; Super flow subsoiler; hydraulic twin spinner manure spreader; discs û two types; harrows; MF Seeder; Cambridge Roller and Duncan Rotatiller.

Jan 1, 1991

By P Louden, C Rothnie, G Showers

Tiwest employs several methods to assess the quality of heavy mineral concentrates in ore and process samples. Mineralogy is determined using a method called MA98, developed in conjunction with JKMRC over the last three years (Zhang and Whiten, 2001). A range of other techniques are also used to characterise ore, heavy mineral concentrates and mineral products. MA98 is the culmination of efforts since 1989 to determine mineralogy from chemical analysis without recourse to heavy liquid fractionation, which has traditionally been used to discriminate between light-heavy , zircon, rutile and leucoxene. The major advance with MA98 is the use of statistical mass balancing for all chemical species, as opposed to reliance on key chemical species for each mineral. Three magnetic fractions are analysed by X-ray fluorescence spectrometry, with a minerals balance performed for each. Heavy mineral concentrates processed by this method include drill samples, process samples from the wet concentrators and Dry Mill, and mineral products. TBE can be avoided for higher heavy mineral grade samples since quartz is determined from SiO2 balance. In this sense the method is sufficiently universal and robust to cope with a wide range of sample types and compositions. The MA98 algorithm provides abundant information in addition to mineralogy, including TiO2 and Fe2O3 grades of ilmenite and leucoxene, and concentrations of weakly magnetic zircon and kyanite. Information such as this is invaluable in tracking different minerals through the processing plants. Other ore assessment procedures used by Tiwest provide for modelling of orebodies by mineral sizings, Fe in zircon, and FeO and U+Th in ilmenite. Microscopy is used to provide important qualitative information such as grain shape, surface staining and degree of cementing. These quality measurements are included with mineralogy in geological ore models and are available for mine scheduling. In using the above methods to characterise heavy mineral concentrates, Tiwest is better placed to predict and monitor plant performance and product quality from any ore zone.

Jan 1, 2001

By P Cameron

The Julius Kruttschnitt Mineral Research Centre (JKMRC) has recently commercialised a variety of new products for the mining industry through its commercial division (JKTech). Although the products cover a wide variety of niche applications, a common thread runs through the Research, Development and Commercialisation (RD and C) process: they have emerged from industry sponsored projects. The development history of JigScan (a control system for the mineral-processing jig) is a good example of how this RD and C process works in practice. It involves building mutually beneficial partnerships between the JKMRC and the mining industry through several incremental projects with one or more industry sponsors. All research projects have objectives to demonstrate but these projects also feature a degree of product development to actively encourage and support the longer-term vision for the mature commercial technology. The process to develop JigScan as a commercial product worked because each incremental project recovered costs, provided an immediate benefit for the sponsor and contributed to the longer-term development objectives of the JKMRC. Integrating development with research need not greatly increase the cost of research objectives generally provides a more robust research outcome for the sponsor and greatly reduces the overall development risk. Successful projects often feature industry mentors actively participating in the RD and C process. Additional funding from government appears to be easier to obtain when such close partnerships with industry are apparent. Finally, the business structure of the JKMRC within the University of Queensland ensures that commercial outcomes, developed within the contractual arrangements of the underlying RD and C projects, are used to benefit and support further RD and C with the mining industry. This paper tells the story of the development and commercialisation of JigScan, and draws conclusions about this kind of RD and C model.

Jan 1, 2000

The paper deals with the problems of grouting methods for fissured-porous rock. The paper describes design procedure, injection process patterns and hydrodynamic testing techni- que to plan grouting programs for fissured-porous aquifers. A number of case histories is given to illustrate the imp- lementation of developed methodology at various mining pro- jects.

Jan 1, 1988

Thank you for that introduction and especially thank you to the organisers for inviting me. I've had a considerable interest in this area and I've had the advantage of an education from Neil on the subject of offering documents as a result of our collaboration together on the Securities Information Review Committee.

Jan 1, 1989

The electrochemical dissolution of gold and other noble metals in hydrochloric acid using alternating current has been investigated. The experimental results show that this technique is efficient for dissolving pure noble metals and offers prospects for their extraction from wastes and poor ores.

Jan 1, 1992

By W Midgley, M Torok, I Canbulat, J Katupitiya, S Saydam, S Akdag

The green energy transition is expected to require a range of valuable minerals, which could be supplied through deep-sea polymetallic nodule mining. Deep-sea polymetallic nodules are mineral deposits with a composition well suited to produce lithium batteries, which are expected to be a necessary energy storage solution (Diouf and Pode, 2015; Paulikas et al, 2020) for the energy transition. By 2050 the annual demand for both cobalt and lithium is estimated to increase by around 450 per cent from 2018 levels (Hund et al, 2023), with the annual demand for nickel being greater than 2 million tons, and copper greater than 1 million tons. Polymetallic nodule mining is well positioned to provide these minerals in the near future. An intricate and comparatively unexplored ecosystem thrives within and surrounding the nodule fields (Smith et al, 2008). Deep-sea mining operations have the potential to disrupt and permanently damage this ecosystem through introduced pollution, artificial noise and light, and habitat destruction. Hence, there is a pressing need for new engineering and scientific endeavours to focus on developing new technologies to reduce any environmental impact from mining.

Sep 1, 2024

Experimentation with new methods, materials and machines to improve primary drilling and blasting is a continuing practice in the hard rock quarry operations of the BMI Group. These experiments will continue in the remote hope that one day we may produce a perfect feed for the primary crusher. As this day is still a long way off, the necessity to break oversize boulders will be a problem to be faced for the foreseeable future. To gauge the efficiency of primary blasting from this point of view, BMI monitor the tonnes of material crushed in the primary crusher for each boulder requiring secondary breaking. Over a period of about 10 years, this figure has improved from 30 tonnes througi the primary crusher per boulder, to 100 tonnes per boulder at our largest operation, which produces in excess of 2 million tonnes per year. Evan with this improvement, 25,000 boulders require secondary breaking each year This paper does not provide the solution to this problem, as like primary blasting, it will have to be constantly reviewed as new products and techniques become available. The paper sets out all of the methods tested or considered for test by BMI and our nnnn1iicinnq nn Chair PffPr.tivPness . Economic

Jan 1, 1978

By J D. van Wees

Preliminary project evaluation is relevant to the evaluation process of the decision makers (or executives) prior to making the critical business choices. Important to the assessment is an integrated sensitivity, scenario and risk analysis at every stage of a mining project. This should include the evaluation of different options taking into account uncertainties. Construction of interactive financial computer models where each element is functionally integrated into a fully integrated life-cycle allows rapid and automatic study of the sensitivity of each element through changes in the value of an input. The scenario analysis is the effect of changing more than one input at a time, organised through scenarios in a decision tree. Risk analysis is an integrated analysis of the effect of all uncertainties of the parameters, using Monte Carlo simulation. Key to the asset decisions process is that the decision maker is provided with the essential integrated decision information. We have clustered this information into several scenario groups. Within each group, two levels of uncertain information are distinguished: discrete scenarios critical for the decisions; and remaining uncertainty within the scenario (risk analysis) which can be modelled by continuous probability density functions (pdfÆs). For an asset, the relevant scenarios in each group and the associated continuous pdfÆs need to be defined. When the scenario groups and associated pdfÆs have been defined for the asset, the decision process can be started by structuring the different scenario groups in a Scenario Tree. A Scenario Tree contains decision and end nodes. Each end node corresponds to a completely defined mine project or asset model. The calculations for each end node result in a set of stochastic realisations for the reserves, production forecast, cash flow, and profitability indicators (NPV, IRR, DPR). Thus, a deterministic and fully probabilistic multi-commodity analysis tool is provided to investigate the sensitivity and robustness of decisions.

Jan 1, 2003

The quantity, quality and detail of project information increases as project development moves from initial scoping level studies, to pre-feasibility and option studies, then definitive feasibility study and basic engineering stages. Data accumulates from metallurgical and vendor testing from various ore types and composites carried out to assess physical characteristics and processing responses of the ore. Over-simplification or assumptions about the orebody for flow sheet development can result in using æaverageÆ information for design. Use of averages of data can have adverse implications on sizing of plant and equipment and consequently on definitive study cost estimates and detailed engineering. In practice, the treatment plant workforce is faced with managing a non-homogeneous or non-average orebody in a variable operating environment that is not always predictable. This paper presents views on how to use the data generated from testwork in project development and for process and plant design. Examples of process design risk or operating risk are presented. Although this topic is applicable to the broad range of process design decision making in the minerals industry, this discussion references comminution, flotation and extraction processes for gold and base metal ores.

Jan 1, 2004

By A Mokhtari, S Gatehouse, N Rutherford

Geochemical exploration continues to play a significant role in new mineral discoveries inAustralia and elsewhere, including terrains where mineralisation is buried or otherwise obscured by regolith cover of various types. Transported regolith commonly restricts the migration of trace elements to surface, especially in arid terrains, presenting a range of problems for traditional geochemical exploration methods that employ surface samples. Regions dominated by transported cover include the northern parts of the Tasmanides in eastern Australia and the Yilgarn Craton which are variably covered by thick alluvium and Mesozoic to Cainozoic sedimentary rocks (Anand and Paine, 2002). An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

Blasting, particularly bench blasting, uses finite length cylinders of explosive close to two free faces. The rock to be blasted is usually intersected by a complex 3-D system of joints. To fully simulate a blast, a 3-D dynamic model is required. It is shown that the static stress distribution around a long cylinder can be reproduced by superposing the static stress distribution of a suitable chain of spheres. Thus, the dynamic results for individual spheres given by Favreau (1969) can now be substituted for the static results to give a dynamic model of the stress distribution around a long cylinder. Comparison of measured and computed waveforms show that the measured waveforms are much more attenuated and dispersed than expected. The consequences for explosive evaluation and design are Discussed.

Jan 1, 1990

Selective leach analytical techniques applied to surface geochemical samples in the search for deeply buried mineral resources gained popularity in the late 1990s. Several commercial assay laboratories introduced their own selective leach methods, adding to the few established commercial methods at that time. Many of these laboratories promoted their methods with orientation data showing favorable responses to both precious and base metal mineralisation, concealed beneath extensive thicknesses of overburden. However, many explorationists remain confused about the utility of these geochemical methods. This confusion is due primarily to the lack of objective orientation surveys over significant mineralisation, comparing all commercially available selective leach methods and to the lack of a creditable theory explaining the formation of these selective leach anomalies. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. An orientation survey was designed to fill the first void û an objective survey over significant mineralisation. With the help of 17 mining companies and assay laboratories, an orientation survey was conducted over five significant covered gold deposits in Nevada, USA , representing over ten million ounces of gold. Hopefully the results of this survey will help provide fuel for those working on the second void û a theory to adequately explain the formation of these selective leach anomalies.

Jan 1, 2008

By Hinrichsen H. D, Rathburn D. R, Stieger W

The present situation in the field of iron ore pelletizing is briefly described with particular view of the Lurgi/Dravo travelling grate process. To meet todays pellet quality requirements with regard to physical and metal- lurgical properties it is often necessary to add basic fluxing materials. It has been de- monstrated that for certain ores, basic addi- tives provide a considerable improvement in fired pellet quality. The production of self- fluxing pellets is becoming increasingly attractive. One Lurgi/Dravo plant is now in operation and another is under construction which were designed for the production of self- fluxing pellets. Self-fluxing pellets may be considered as the primary or exclusive blast furnace burden and the installation of a sinter plant is not necessary if the pellet plant-can handle all in-plant fines. Reference is made to the first pellet plant utilizing iron ore concentrate, in-plant fines and basic flux. The use of solid fuel for pellet indura- tion is discussed because of the increasing prices and possible shortages of heavy oil and natural gas. Since there is a strong tendency to increasing plant capacities, the design fea- tures of travelling grate pelletizing plants for productions up to 6 million tonnes are Discussed.

Jan 1, 1974