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By M A. Rhamdhani, R Z. Mukhlis

Removing the ledge formation in the Hall-Heroult cell during the electrolysis process may significantly reduce the energy requirement of the aluminium production process. In the absence of the ledge, however, the sidewall-material types become heavily restricted since the cryolite is very corrosive at the electrolysis temperatures. This paper study the corrosion behaviour of sintered nickel ferrite, nickel aluminate, and magnesium aluminate refractories (as possible candidates for sidewall material) in molten aluminium and cryolite melts with various alumina content at 980°C. Immersion tests of refractories with various porosity were conducted to assess the suitability of the refractories in the corrosive environment of the electrolysis cells. Microstructural change of the refractory after immersion were analysed using secondary scanning electron microscopy (SEM). Sampling of the melts were taken at 0, 10 min, 30 min, and each hour up to 6 hrs, and subsequently analysed by Inductively Coupled Plasma (ICP) spectroscopy. Based on the projected concentration of the refractories constituents in the melts, it was predicted that the corrosion rate of NiFe2O4, NiAl2O4 and MgAl2O4 in cryolite with 11 wt per cent Al2O3 were 461 × 103, 1.03 × 103, and 798 × 103 cm/a, respectively. Much lower corrosion rate of 2.3 cm/a for NiFe2O4, 2.6 cm/a for NiAl2O4 and 0.3 cm/a for MgAl2O4 were predicted if the refractories in contact with aluminium melts. Erosion played an important role in the corrosion as the concentration of the refractory constituents in the melts were beyond its solubility limit. It is therefore crucial to increase the densities of the refractory and improve its wetting characteristics.

Aug 21, 2024

By Alexander RB, Hollis AJ

The magnitude of the payloads carried by mine haul trucks can have a strong influence on the mine production rates and costs. Consequently control of truck payloads is highly desirable, but in many mines the unavailability of means for measuring payloads reliably, accurately and easily has resulted in a low level of control over truck payloads. Consideration is given to two techniques which are applicable to the measurement of payloads carried by mine haul trucks, namely truck weighing and direct measurement of payloads with truck based systems. Accuracy assessments for two types of truck weighing platforms and two prototype truck based direct payload measurement systems are provided. Results show that weighing platforms based on hydraulic components have proved inadequate, while strain gauge type weighing platforms can estimate payloads to within 2% of true payload when installed, maintained and used correctly. The assessment of the two prototype truck based direct payload measurement systems shows that a high proportion of payloads were estimated to within 5% of the payloads derived from accurate weighing platforms and that these systems appear to have the potential to provide convenient and accurate measurement of payloads. This should enable payloads to be much better controlled than has been possible to date. Predictions of the effect of payloads on production rates and some components of truck haulage costs are possible and some typical results are presented. Accurate prediction of the effect of payloads are not yet possible for some major components of truck haulage costs.

Jan 1, 1986

By C Parihar, R Garg, A Bhandari, S Bhandari

Blasting can impact the efficiency of entire downstream mining operation. Individual technology solutions for blasting have been available in the industry for many years but all of them only cater for certain aspects of blasting. Many of them are based on individual research and/or experiences. Some of the available software solutions are not suitable to be used in the field as that they need advanced skills or tools. Also, most do not take technology advancements like mobility, advanced data analytics, web solutions and integration into consideration. Hence, no technology platform is currently present in the industry that addresses all potential needs a blaster may need in an integrated manner.This paper presents an integrated solution that takes care of all aspects of blasting – design blasts according to mine plan; collect data after drilling has been carried out (as there is often difference in designed and actual drilled hole locations in the field); predict blast results in terms of fragmentation, flyrock, ground and air vibrations, wave front reinforcement and flyrock distance; and after assessment, allows changes in charging, delay timing and sequence. The technology solution is a secure, cloud-hosted, web-based software-as-a-service solution that can be accessed from anywhere. Also it has a mobile app, which is available for both Android and iPhone/iPad. The mobile app is also integrated with the web-based solution using application programming interface calls to the central data repository.Case studies for two limestone mines are presented where this solution is being used in its initial format. This software platform enabled analysis of the outcome from a previous blast pattern and then subsequently allowed optimisation of blasting operations based on historical data. Uses of this platform have resulted in improved key performance indicators in these two limestone mines. The mobile app as part of this platform enables extensive field blast data capture and analysis and also various predictions before a blast. Data collected include blast parameters, individual hole charging, initiation pattern, videos, photographs and vibration records for analysis/reporting. The key features of the solution are a blast designer, a detailed blast data collection/analysis and a series of environmental predictors. These predictors give blast results in terms of fragmentation, flyrock, ground and air vibrations and wave front reinforcement and take remedial steps before blasting to optimise and control adverse environmental impact. Many features, such as fragmentation predictor and mobility solution, are completely unique features that are not available elsewhere in such a field personnel-friendly manner.CITATION:Bhandari, S, Parihar, C, Garg, R and Bhandari, A, 2015. An integrated technology solution for optimised and environmentally-controlled blasts, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 393–400 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By C Boyle

Brockman 2 mine is located in the Pilbara of Western Australia and is operated by Rio Tinto Iron Ore. Mineralisation is hosted by synclines where there is structural complexity to focus fluid flow. Mineralisation is hosted by the Brockman Iron Formation. Mining is on 10 m benches and blastholes spaced at 6 - 8 m apart are geologically logged, sampled by shovel cuts, and assayed using X-ray fluorescence for ten chemical variables. Blast blocks are digitised by mine geologists to assign destinations of material within blasts. Resource evaluation drilling is on a spacing of 50 m × 50 m across known mineralisation and consists of recent reverse circulation drilling and older open hole percussion drilling. Sampling of resource evaluation drilling is by rotary splitters or riffle splitters, and assaying is by X-ray fluorescence for ten chemical variables. Ordinary kriging of resource evaluation produces a long-term resource model. This study examines whether mine planning would be improved by using a blasthole estimate to extrapolate grades into deeper benches and merging the blasthole estimate with the long-term model made using resource evaluation drilling. The two estimates are merged into one model using an inverse weighting based on kriging variance. However, reconciliation results in a test bench show the original estimate made using resource evaluation drilling more closely matches mine geology block outs than does the merged model. This is due to a local trend of more high grade and higher iron grades of high grade in the area. The blasthole estimate of deeper benches must use extrapolation and it is diffi cult to take local trends into account. In contrast, the estimation using resource evaluation drilling is mainly interpolation and is better able to handle local trends.

Jul 11, 2011

By X Liu

The crystal chemistry of carbonate in Ca apatites, including Na-free and Na-bearing hydroxylapatite (CHAP) and Na-bearing fluorapatite (CFAP) and chlorapatite (CCLAP), has been investigated by Fourier transform infrared (FTIR) spectroscopy and single-crystal X-ray structure, using crystals synthesised from carbonate-rich melts at 1 GPa, 1400 - 1000¦C. The carbonate ion substitutes for both the X (OH, F, Cl) anion species in the apatite channel (type A carbonate) and the phosphate group (type B carbonate). The type A carbonate ion is oriented in the channel with two oxygen atoms close to the c-axis, and the type B carbonate ion is located close to the sloping faces of the substituted phosphate tetrahedron, with details varying with composition series. Sodium promotes the uptake of type B carbonate and also has a profound effect on FTIR spectra. Crystal compositions correspond approximately to the substitution formula Ca10-(y+z)Nay z[(PO4)6-(y+2z)(CO3)y+2z][X2-2x(CO3)x], with x + y up to 1.0 and z + 0.0 for CHAP, x + y + 4z + 0.4 for CCLAP, and x + y + 2z + 0.1 for CFAP, for equivalent conditions of synthesis. The sodium cation and A and B carbonate ion defects are locally coupled in all three composition series to facilitate charge compensation and minimise the effects of spatial accommodation. Synthetic Na-bearing type A-B CHAP with x + y + 0.5 has a similar chemical composition and FTIR spectrum to biological apatite.

Jan 1, 2008

The green field discovery of a two million ounce high-grade refractory gold ore deposit in the Indonesian Province of Sulawesi Utara, led Newmont to utilise its proven technical expertise in dry grinding and whole ore roasting to develop a 2000 tonne per day, 160 000 ounce per year operation in this remote and picturesque location.Located at an elevation of 250 in above sea level and ten kilometres to a deep water natural harbour, the hard rock open pit mine, process plant and infrastructure facilities were built to budget at a capital cost of US$132 million. The plant was commissioned with oxide ore, with the first gold poured in March 1996 and with refractory ore in January 1997. The operation rapidly met its production targets because of extensive forward planning and training programs developed for the local workforce. The presence of steep topography, fertile coastal plains, high rainfall, high seismicity of this location led to the decision to dispose of neutralised tailings in deep water off the coast instead of impounding tailings in a dam. This paper describes the development of the project and the challenges in developing a gold operation in a remote location which lacked infrastructure, the steps taken to ensure a smooth commissioning, and the selection of the workforce to operate a technically sophisticated facility.

Jan 1, 1997

This study is to compare reinforcement of rebar and spiral bolts using laboratory pull-out test. For this purpose, the pull-out test was performed in laboratory for a curing period of 7- and 28-days. Based on the results of the laboratory pull-out test, the pull-out load of two support members rapidly increased with displacement until the breakpoint and then gently increased with displacement. The maximum pull-out load of spiral bolt was larger than that of rebar bolt. This implies that a spiral bolt is more stable than a rebar bolt for securing the stability of a ground or rock mass when a support was installed in a ground or rock mass under the same condition. In addition, the maximum external pressure of two support members increased with pull-out load and with displacement and the distribution of external pressure was commonly larger at the upper part than at the lower part of specimen. This indicates that the bond failure location by pull-out load should be mainly occurred at the surface portion of specimen. In conclusion, the reinforcing effect of a support depends on a curing period and a type of support member, and reinforcement of a spiral bolt is more effective than that of a rebar bolt.

Dec 6, 2010

The statistical nature of the variability in detonation times of pyrotechnic delays is discussed, and how to evaluate the probability of required detonation intervals is shown. Some methods (analytical and stochastic) are given for designing blasts to ensure that any adverse effects on the variability in the delays is taken into account and minimised. Using computer models of blasts, detonation simulations can be used to check the initiation sequence for the probability of sequence reversals, indicating areas of high blast damage potential. Charge consumption rates, which relate directly to the resulting vibration levels, can be examined for their susceptibility to variation from delay variability. Models that synthesize vibration waveforms for production blasts, when taking delay variability into account, indicate the difficulty in vibration level prediction.

Jan 1, 1992

Slide presentation at conference

Jan 1, 1996

By Huleatt M, Perkin D, McLeod I, Mock C, Pratt R, Gourlay A, Timoney E, Knight N, Ward J

Generally speaking, Australia's reserves of its more important minerals (in terms of export earnings) are adequate to sustain forecast rates of production to the year 2000. The rate of forecast production increases of these commodities (aluminium - whether as bauxite, alumina or metal, black coal, iron ore and ferro-alloy minerals, base metals, tin, uranium, and mineral sands) reflects a well- ordered and sustained growth phase of Australia's mineral industry.

Jan 1, 1981

The article, as written, represents a short account of the treatment of the base bullion from the Broken Hill ores, as carried on at Port Pirie, for the recovery of lead, silver, and gold, and for the treatment of by-products. Appended is a short description of the chief facilities of plant which have been adopted to overcome the main difficulties in the refining of lead the Howard press and stirrer. The article is within the limit prescribed by the regulation for the prize offered by the Australasian Institute of Mining Engineers, comprising 30 pages, containing an average of about 200 words per page, exclusive of analyses, photographs, and sketches.The writer desires to thank those to whom he is indebted for their- kindness in affording him every facility possible to obtain the information which he required for the success of such a paper-viz., Messrs. Robertson, Leavens, and Gronow, of the Broken Hill Propritary Co. Limited, at Port Pirie, and Mr. Crowther, of the Adelaide School of Mines, to whom he is indebted for photographs. The difficulty of obtaining fair samples of gold drosses, and the inability to obtain particulars of fuel consumptions, prevents the paper from being as complete as one would wish. The limited length precludes detail, except in more important parts.

Jan 1, 1907

Large GDP increases in the Pacific Rim countries have been accompanied by similarly large increases in demand for oil products. In the case of residual fuels, this demand has been tempered by the substitution of other energy products such as coal or gas.In the region's developing and newly industrialised nations, it has not been possible to make the very large investements in infrastructure which allow other energy sources to be used for transportation. As a result, GDP growth has been mirrored in the demand growth for automotive fuels. Other non-sustitutable products such as lubricants have also benefitted by the region's GDP growth.The combination of a number of years of sustained growth, coupled with increasing quality requirements is now stretching the upgrading capacity of the region's refineries. If, as seems likely, the region continues to enjoy a high GDP growth rate, then this will be accompanied by increasing reliance on finished products coming out of the Middle East. The owners of the most simple form of refinery in which crude is simply distilled and the naphtha reformed into petrol will face major capital investments. If they decide not to bear this cost, they will face increasing problems in selling their surplus residual fuel oil at an economic price. Quality will become an increasingly important issue. Not only in the well publicised areas such as unleaded petrol, but also for products such as lubricants which play a major role in the efficiency of modem equipment. Quality of service such as hours of opening, ease of access, and service station facilities will also become increasingly important as the oil companies use these to attract customers and gain brand differentiation.

Jan 1, 1990

By T Ireland, S Eratne, W Newns, P Spies

The approach to risk management during the procurement of major projects often has a significant outcome on the ultimate delivery of a project. The NZ$1.4 B Waterview Connection project is the largest and most complex project yet undertaken by the New Zealand Transport Agency (NZTA) and the procurement process for an alliance contract was refined to provide compliance with the International Tunnel Insurance Group (ITIG) Code of Practice for Risk Management of Tunnel Works (TCoP). The principle of shared risk within an alliance incentivises a common understanding of project risks prior to finalising the alliance agreement and therefore enables superior risk management through design, construction and beyond. Risk management practices need to be instigated well in advance of commercial phases, so that commercial competition does not lead to a significant elevation of project risk. In particular the practice of gaining commercial advantage by taking on a potentially unmanageable level of risk is one of the outcomes to be avoided by the TCoP.During the procurement phase the NZTA placed high value on design and construction mitigation measures proposed in order to address ground risks, as is appropriate for a major tunnel project. In order to achieve alignment on the level of geotechnical risks an Alliance Geotechnical Baseline Report (AGBR) process was developed.This paper describes the measures taken during the procurement process to achieve certainty with respect to outcomes and minimise project risks whilst also achieving value for money. Refinements to the procurement process to ensure compliance with the TCoP prepared by the International Tunnel Insurance Group (ITIG) are described along with the AGBR process applied as part of a suite of measures to achieve a successful procurement outcome.CITATION:Ireland, T, Spies, P, Eratne, S and Newns, W, 2014. Risk management and use of a geotechnical baseline report for a competitive alliance procurement?process, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 553–562 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By R Verreet

In April 2000 Mount Isa Mines installed hoist ropes of a new design on the double-drum winder at their P49 shaft. The ropes, CASAR Duroplast, were about three times as expensive as the previously used triangular strand ropes. The P49 shaft is situated at Mount Isa MinesÆ George Fisher Mine, located some 30 km north of Mt Isa. This shaft used the tried and proven 6 x 33 triangular strand style ropes. The rope life attained by these ropes at the time was acceptable due to many years of satisfactory performance. The following study indicates the improvement of service life using CASAR Duroplast rope in P 49 shaft, which depends on shaft and winder parameters of that particular shaft and cannot necessarily be generalised to other shafts.

Jan 1, 2005

By Dods G. H, Hewitt W. V

Ashton Mining Limited is currently one of the active companies undertaking gold exploration in Indonesia. Presently 7 Contract of Work areas are being explored for hard rock and alluvial gold. Hard rock exploration is focussed on the Tertiary volcanic arc terrains in which a variety of epithermal mineralisation styles have been identified. At the regional stage remote sensing techniques using Landsat, Spot and SLAR imagery where available, and photogeological studies are carried out in parallel with regional reconnaissance fieldwork programmes. These involve geological mapping and geochemical drainage sampling. Remote sensing techniques have proven useful in both the extrapolation of known geology and the identification of tectonically favourable settings as controls to mineralisation and volcanicity. The variety of mineralisation styles and settings is reflected in the highly variable geochemical signatures encountered. This has necessitated the refinement of sampling methods and sample preparation techniques for pan concentrate, stream sediment and soil samples in specific project areas. At the detailed prospect stage, mapping with particular attention to structural controls, wallrock alteration assemblages identified by petrog- raphy and XRD clay mineralogy, have proved useful in focussing drill targets. Drilling to date has utilised conventional diamond core drilling methods, the use of lightweight, man-portable "Winkie"-type rigs and hammer auger bedrock sampling systems. Geophysics methods successfully employed on various projects have included airborne magnetics and radiometrics, detailed ground magnetic surveys, VLF-EM and SIROTEM.

Jan 1, 1991

By H J. Ross, R K. Beatson, T J, W R. Fright

Traditional method of explicitly defining three-dimensional (3D) ore-waste and geological boundaries relies heavily on a time-consuming process of manual digitisation. This method of modelling can be best described as surface modelling, as complex surface geometry is built up by digitising points that lie on the surface. With the advent of fast 3D interpolation methods, however, construction of geological surfaces using volume functions is now a practical alternative to explicit modelling of surfaces. Unlike explicit modelling, surfaces contained in volume functions are not explicitly defined or digitised. Instead the existence of surfaces in the volume function is implicit, thus the process of modelling surfaces from volume function is called æimplicit modellingÆ. Based on recent advances in fast scattered data interpolation methods, implicit modelling first defines a continuous three-dimensional function that describes the grade or rock distribution. This volumetric function is interrogated for a grade value, or a geological surface, thus allowing the extraction of the 3D object to be automated and eliminating the need to manually digitise surfaces. Since the function is continuous throughout space and does not depend on a mesh or grid for its definition, the extracted geological or grade wireframes can be constructed at any desired resolution in the specific volume of interest. The volume modelling method can work on scattered drillhole data of any data density, including processing combined information from dense grade control data as well as sparse resource drilling. It offers distinct advantages over surface modelling, including: being able to wireframe geological objects that may take days to digitise in tens of minutes; substantial improvement in modelling accuracy; and the ability to generate conditional models rapidly allowing mining risks inherent in geological modelling to be examined.

Jan 1, 2003

Among countries afflicted with insLantaneous outbursts of coal and gas, Australia is noteworthy because of lesser disturbances of the seams and of the occurrence of CO2 in the seam gas from place to place. Research sLarted with the 1954 occurrences at Collinsville and Metropolitan Collieries leading to early publications reviewing the problem, describing occurrences and assessing variations in proneness factors in the two affected coal basins.The basic requirements for proneness include coals of high gas sorptive capacity, high ground stress, use of a mining method which provides higher stress concentrations and limits emission of seam gas, including high rates of advance. With CO2 in the seam gas proneness is greater.The mechanism is complex and not fully understood, but involves the coal, the roof, the floor, the gas, the mine opening, the ventilation, the kind of work and the rate of work. Geological disturbances such as faults and dykes increase proneness and tend to localise occurrences. On-occurrence of outbursts in some mines is difficult to explain.Outbursts are seen as a continuing threat to modem deep Australian mining of high rank coal.The simplest contributory factor to reduce is gassiness - despite the low permeability of outbursting coals - and present practices are showing promise. The greatest challenges for the future are partial degasification to below a known threshold figure and confirmation that this reduction is achieved and identification of anomalous geological structures ahead, the most likely locations for instantaneous outbursts to occur. The advances made to date give promise of a future with reducing experiences of uncontrolled instantaneous outbursts. For the Bulli seam particularly, working to achieve prediction and prevention is most urgent.

Jan 1, 1993

Declines for both access and rock haulage are replacing shafts for mining relatively shallow deposits of down to 1000 m below surface. Where the orebody does not outcrop and where surface access may be restricted, it is often necessary to drive long dead end headings before a connection can be made back to surface and a ventilation circuit created. In hot tropical areas and where large diesel powered equipment is used for mining, heat may also be a problem at these relatively shallow depths. The normal design criteria based on statutory limits and good practice used to evaluate ventilation and cooling requirements in terms of air velocity, dust, gases, diesel exhaust dilution, re-entry after blasting and heat stress are described in this paper. These are then used to design and cost alternative auxiliary ventilation systems that include leakage based on general fan performance curves and typical duct systems. The implications of the current European Community recommendations regarding nitrous fumes are also briefly considered. The actual problem relates to a 2100 m long decline that may have to be extended to 3000 m long without a connection to surface or through ventilation and is located in a hot tropical area where the surface wet bulb temperatures may exceed 25¦C for more than a third of the summer period. Once the preliminary ventilation design is completed, the auxiliary ventilation system can be modelled and simulations undertaken that incorporate heat and moisture transfer routines with the objective of determining the cooling load and amount of refrigeration required. Cognisance is taken of cyclic diesel operations and the thermal flywheel effect of the surrounding rock on the wet and dry bulb temperatures resulting from these operations.A suitable modular cooling system located at the portal is described and optimised with capital and operating costs of both the ventilation and cooling systems provided.

Jan 1, 2005

By Aziz NI

There are a number of methods available for the determination of the fracture toughness of rock. Some of the most recognised methods include the hollow pressured cylinder, the short-rod, the chevron - edge-notched round bar in bending and the disc-shaped compact specimen. Most of these tests are difficult and expensive to conduct. In this paper the simple Brazilian testing of discs for tensile strength has been used to determine their fracture toughness. Tests were conducted on six different rock types and the values of the fracture toughness obtained for each type are in close agreement with the results of the well recognised the chevron edged types. Details of the tests, and analytical validation of the technique, are presented

Jan 1, 1992

By I Sherrell, R Jain

Worldwide iron ore feed grades are trending downwards and will continue to do so with the increasing difficulties of upgrading ores. This has led to operations looking for ways to capture current tailings that still contain valuable material. In the past, these were acceptable to dispose of, but this practice is no longer economically feasible. With the increasing trend of re-mining previous tailings deposits that could be decades old, new equipment designs have been introduced to upgrade current or historic beneficiation plants. These designs can effectively upgrade these tailings to saleable products.Outotec conducted test programs for upgrading iron ore tailings from flotation rejects, thickener underflow or tailings dumps on samples provided by customers around the globe. The studies utilised Outotec’s SLon vertically pulsating high-gradient magnetic separator in combination with preprocessing equipment such as low-intensity magnetic separation, screen or scrubber and flotation for downstream processing of the magnetic concentrate. A review of the equipment required to economically process these tailings is provided, along with testing data and industrial implementation examples. The effect of different operational and design parameters on Fe grade and recovery from processing each tailings sample has been highlighted.CITATION:Jain, R and Sherrell, I, 2015. Iron ore tailings reprocessing to maximise ore production, in Proceedings Iron Ore 2015, pp 149–158 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015