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By D J. Thobaven

Project financing challenges caused by declining commodity prices have heightened the need to improve project metrics such as minimising capital payback and maximising net present value (NPV). Khnaiguiyah Mining Company (KMC) recognised the need to improve early cash flows at their Khnaiguiyah zinc-copper project after initial studies showed the project could not provide the desired financial outcomes necessary to compete for investment dollars in the current market.A significant improvement to the project cash flow in early years was realised through simultaneous optimisation of cut-off grade, mining sequence and strategic stockpiling. This improvement was achieved by accelerating mining in the pits, stockpiling lower value material and feeding higher value material directly to the plant. The schedule required higher mining and stockpile capacities than the sequential mine plan although minimal change occurred in the definition of ore and waste as measured by tonnes and grade. The practicality of the strategic schedule was demonstrated by implementation in the production plan with excellent conformance.CITATION:Thobaven, D J, 2014. An application of simultaneous optimisation – improving the payback period of a zinc-copper open cut project, in Proceedings Orebody Modelling and Strategic Mine Planning Symposium 2014 , pp 137–144 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 24, 2014

A Kellogg type computer model of the slag fuming process is applied in reverse to derive some thermodynamic properties of components in lead blast furnace slag. At 1200¦C, the average activity coefficients calculated were 3.40 (S.D. 0.50) for ZnO referred to the pure solid; 0.657 (S.D. 0.022) for PbO referred to the pure liquid; for the ratios y 3.175 y (referred to the Feo.9450, Fe304 pure solids) 4.19 (S.D. 1.15), and for yCaS/ 1CaO (referred to the pure solids) 5.10 (S.D. 2.96). Statistical relationships were derived for these activity coefficients and ratios as functions of the composition of slag, which contained in molar percentages 1.9 - 12.6% ZnO, 19.8 - 24.9% Fe0.9450, 0.9 - 1.6% Fe304, 0.002 - 1.9% PbO, 16.1 - 18.6% CaO, 25.9 - 31.0% SiO2, 4.8 - 5.5% MnO, 9.2 - 10.3% A101.5, 1.2 - 1.4% CaS, and 5.1 - 9.6% "Mgo" (the balance).

Jan 1, 1980

By W Valery, A Jankovic

A growing demand within the minerals industry for sustainable development and the introduction of carbon taxes have resulted in a significant focus on improving the energy efficiency of comminution circuits. However, in this drive for improved energy efficiency the role of classification has been overlooked. Inefficient classification and large recirculating loads reduce circuit capacity, result in over-grinding and higher specific energy consumption.It is well understood that classification increases mill capacity; therefore, closed ball mill-cyclone circuits have become an industry standard. However, due to limitations in cyclone classification efficiency, the optimum recirculating load is limited to about 250 per cent. A simple relationship quantifying the effect of classification efficiency and recirculating load on grinding circuit capacity is presented in this paper. The possibility of improving the capacity of ball mill circuits by improving classification efficiency is discussed, considering the current practical limitations of classification equipment. Simulation tools were used to evaluate circuits with cyclones and with high frequency screens to identify opportunities to improve energy efficiency. The investigation also identified potential benefits to flotation recovery due to a reduction in over-grinding.CITATION:Jankovic, A and Valery, W, 2012. The impact of classification on the energy efficiency of grinding circuits - The hidden opportunity, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 65-70 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By Hoberg H, Schneider FU

Flotation tests were conducted with galena, quartz and with synthetic mixtures of the two, in different ranges of grain size, and with different process parameter variants. Physico-chemical analyses were also carried out on surface energy and on xanthate adsorption on galena with different grain sizes. Reference will also be made to hydrodynamics, interfacial chemistry and the influence exerted by grain size in flotation.

Jan 1, 1993

Attempt has been made to determine the nature of charge on activated carbon surface by studying the electro-kinetic properties of the carbon in the presence of cations, anions and aurocyanide solutions. The zeta-potential measurements were made in the presence of individual ions and also in combinations. The cations and anions chosen were those commonly associated with gold bearing ores in Kalgoorlie area. It was found that the iso-electric point of Norit Carbon was at pH 4.45; below this pH the charge was positive, while above, it was negative. In the absence of gold cyanide solutions and in the presence of individual cations the i.e.p. shifted to the alkaline range (pH 7.2-8.5) while in the presence of anions the i.e.p. was shifted to less than pH 3.5. In the presence of aurocyanide solutions, the iso-electric point was still in the acid region irrespective of whether anions or cations were present. The probable mechanism for such a behaviour has been attempted after measuring the specific conductivities of solutions before and after gold adsorption, by studies using the electron- probe-mirco-analyser, and S.E.M. on the carbon surface.

Jan 1, 1982

By Y Zhang, Z Zhao

The green production of the steelmaking process has urgent requirements for fluorine-free fluxes. In this article, a new solid waste-based slagging flux was applied in the external dephosphorisation test of low silicon hot metal to replace the traditional fluorite-lime dephosphorisation slag. The results showed that under laboratory conditions, the new flux was utilised for smelting low-silicon molten iron with a phosphorus content of 0.10~0.13 wt per cent, the temperature of the molten iron was 1350°C and the slag amount was controlled at 2 per cent. Within ten minutes of smelting, the dephosphorisation rate of the molten iron reached more than 50 per cent. When making slag with new flux, the slag melting time was about 40 seconds and the P2O5 content in the final slag was higher than 8 wt per cent. In the industrial test of a 150 t molten iron ladle, under the same molten iron conditions, an out-of-furnace dephosphorisation test was conducted in the Kambara Reactor (KR) process. The flux material consumption per ton of steel was 8~10 kg. Within 15 minutes of smelting, the dephosphorisation rate of the molten iron was about 30 per cent. During flux slag making, the slag melting time was about three minutes and the P2O5 content in the final slag was higher than 6 wt per cent. This new solid waste-based flux has significant cost advantages and outof- furnace dephosphorisation effects and is expected to become the benchmark for a new generation of fluorine-free steelmaking fluxes.

Aug 21, 2024

By B Roache, J O’Brien, M Gray

Admixture use in cement products is commonplace in the construction and mining industries. Many Australian mines have an operational concrete batch plant and stock hydration control and water reducing admixtures. The benefits of admixture use, especially in shotcrete is understood and well documented. Cemented rock fill (CRF) is used to fill stope voids and create stable vertical and undercut surfaces at some Australian mines. These mines generally mix rock fill with a slurry of cement and water without the use of admixtures. Recently published work on optimisation of CRF mixes has mainly focused on the strength increases associated with changes to the mix grading proportions by the addition of fines, but not focusing on the potential benefits of admixture use. Admixture use in CRF may be the simplest CRF optimisation method, as the admixtures will often be added by the push of a button at the batch plant. A CRF testing program was undertaken to test the benefits of admixture use in terms of strength gain, using hydration control additives (HCA) and high range water reducer (HRWR) admixtures. Rock fill gradings were strictly controlled in the test process to allow clear definition of the difference admixtures provide in compression at 28 days. The testing results define admixture associated strength gains in a 6 per cent general purpose (GP) cement by dry weight CRF mix (131 kg of cement/m3). Costings have been developed to allow a mine operator to understand the cost benefits of admixture use in CRF due to reduced operating costs. Operational efficiency advances and a suggested admixture implementation plan for CRF optimisation is offered.

Nov 29, 2022

A brief review of the problems in ventilating and cooling deep and hot Australian mines is presented. An overview is given on the development of the controlled partial recirculation concept. The main part of this paper describes the first majo

Jan 1, 1994

By Isobe K, Muchi I, Hsieh YS

Theoretical and experimental studies have been made-to clarify the physical and chemical behavior of the tuyere combustion zone of blast furnace. Gas streamlines around this zone were visualized by the use of the two-dimensional equip- ment. Close agreement between the observed stream- lines and the calculated ones is found. The three- dimensional experimental studies have revealed that there exists a so-called dry zone in the neighbor- hood of the raceway and the trickling liquid be- haves approximately like a continuum. A kinetic model is develdped to describe the behavior of coke combustion in the tuyere zone. The model is based on the reaction kinetics, the differential balances of heat and mass, and the mechanics of gas flows. Regarding-the-axial distribution of gas composition in the tuyere zone, good agreement is obtained be- tween the model prediction and the data observed in a working furnace by the other investigators. Cal- culated results-show that the maximum consumption of coke occurs at the intermediate region of the raceway. For the blowing of oxygen-enriched or high -humidity blast, the position at which the maximum consumption of coke occurs is shifted toward the tuyere nose. Similar effect is found when the par- ticle diameter of coke in the tuyere zone is de- creased. The solid flow pattern around the tuyere combustion zone was visualized by the use of the two-dimensional equipment in which the sublimation of dry ice particles in front of the tuyere was

Jan 1, 1981

In recent years new instrumentation and digital technology have Wrote possible a new facet of goo-physics: broadband seismology. From digitally record-ing networks and arrays. broadband scistnograrns of body waves that are flat to displacement and veloc-ity in at least the frequency range from 0.01 to 5.0 liz can now be routinely obtained for most carthquakes of magnitude greater than about 5.5. In contrast to data from conventional narrowband seismographs, broad-band body waves have sufficient spectral information to nvest,igate the many frequency-dependent eflects that may arise from source finiteness and from wave prop-agat ion phenomenon. Besides the usual parameters of depth. moment and focal mechanism, broadband data have sufficient spectral information to provide estimates of radiated energy, associated stresses and the frequency dependence of source parameters. Moreover. teleseis-mically recorded broadband data and near-field strong motion accelerograms overlap in the frequency band be-tween about 0.1-2.0 Hz. Thus. v it h broadband data it is possible to connect far field and near field data in order to make estimates of acceleration for almost any seismically active region of the circum-Pacific.

Jan 1, 1990

By Russell P

Polyurethane resin (PUR) is extensively used in almost all coal producing countries. On the local scene, PUR components suitable for underground application were selected and subsequently, trials were carried out at several coal mines. This paper describes the work at Pikes Gully Colliery (B.P.3Coal), where water flow rates of up to 4.5 m (1000 gallons) per minute, were reduced to 1-1.5 m /minute at the tirst stage of application. Subsequent trials were carried out at West Cliff Colliery (Kembla Coal and Coke). A variety of PUR chemical mixtures were tested in coal ribs and in the roof of intersections and roadways. The trial results are presented with all particular details. Using the PUR injection method, the roof, at the most difficult intersection, was stabilised and 'de-bonded' roof bolts were re-sealed. At Pikes Gully and West Cliff Collieries, 2 tonnes and 3 tonnes of PUR chemicals were injected, respectively. The technique, primarily based on German experience (Bergwerksverband), was used by Delta Control Systems Pty. Ltd. ACIRL was closely associated with the trials, which were monitored by installation of the measuring Stations.

Jan 1, 1986

By Mallett CW, Hammond RL

Geological maps of the Pacific Rim recently published by the Circum-Pacific Council for Energy and Mineral Resources have provided a useful perspective from which to view modern plate interaction and the evolution of modern fold belts. An important lesson from any study of modern plate interaction is that of the normality of change. The chaotic is more usual than the simple. Present day convergent margins with mixed characteristics are measures of this chaos. Indeed, the character of less than one third of the present length of the Pacific Rim can be ascribed to conventional models of plate interaction. Another lesson is that of the great mobility of oceanic crust. Enormous areas of the Pacific may not be represented in future fold belts developed at convergent boundaries unless normal consumption processes are disrupted, and even then only by linear zones a few kilometres wide. The axes of divergent boundaries creating Pacific Ocean crust have been equally mobile, with new spreading sites taking over from older sites through time. Divergent boundaries, whether active or inactive, consist of oceanic crust, and may be wholly consumed at collision sites with convergent boundaries. Their only potential contributions to fold belt evolution are transforms and magmatic activity. It is this transform component that can provide us with a mechanism to explain the apparent contradiction of both compressional and extensional features occurring together in a developing fold belt. Reconstructions for the SW Pacific are used to demonstrate that the fold belts under construction during the last 4% (Jurassic- Recent) of geologic time have involved interaction between convergent, divergent, and transform boundaries. In the last 15% of earth history (Late Proterozoic-Recent), many enigmatic features of the geologic landscape in Eastern

Jan 1, 1987

By Barnes R. G, Agostini A, Lewis P. C

The Mineral Resources Audit is a five-year Program established to produce a comprehensive and objective assessment of the mineral resources of New South Wales, including prospective resources. The goals of the Program are to improve planning and land use decision-making; attract exploration and minerals related investment; help the Department to identify and fill gaps in knowledge; and develop methods to identify and quantify resource potential and prospectivity. To achieve the goals of the Audit it is necessary to assemble and enhance a large amount of information and it is necessary to spatially analyse this information using computer-based Geographic Information Systems (GIS) which allow the collection, storage, transformation and display of large quantities of spatial data. An extensive range of both map-based and textual data can be employed in spatial analysis and resources and geoscience modelling. In order to use this information, data sets have to be corrected and standardised. Many data sets need to be classified. An objective of the Audit Program is the spatial analysis of the State, region-by-region, and the release of cleaned-up multiple digital data sets as packages which include upgraded mineral deposit information, 'seamless' geological map layers showing lithology, structures and stratigraphy, and processed and classified geophysical map layers. These regional packages are important reference sets for the mineral resources industry and will assist delineation of regional exploration targets.

Jan 1, 1995

By L Ventura, M Almond

The Pueblo Viejo project in the Dominican Republic installed an innovative sample system on its reverse circulation (RC) drilling rig during commissioning and subsequent commencement of operations. As knowledge of the orebody increased with mining and plant production, cost pressures became apparent that raised questions concerning the continued use of RC drilling versus blasthole sampling for ore control.To justify the continued use of RC drilling for grade control, an in-depth study was undertaken to determine the quality of the sample and prove its value-add to the operation.To investigate the differences in sample quality, a complete bench trial was initiated across both ore pits to compare RC drill results with blasthole assays on a side-by-side basis. The results indicated that based on ore block comparison between RC and blasthole sampling, RC identified an additional 20 per cent of high-grade (+ 4.5 g/t Au) ounces.Previous work indicated that Au, Ag and Cu were all elevated in the drill fines at Pueblo Viejo (Goers and Almond, 2012). This previous test work did not consider the quantity of fines in an RC sample therefore new test work was undertaken to include particle size distribution analyses. This study would determine if the inclusion of fines in the sample was occurring and compare the quantity of fines in the sample against other sample systems and blasthole samples.Comparisons between RC samples and blasthole samples indicate that for the RC samples a range of 30–35 per cent of the sample passed 300 mesh as compared to blastholes where the range of the sample passing 300 mesh was 15–30 per cent.This paper includes a case study on the importance of accurate samples and how they have impacted throughput through the pressure oxidation process plant at Pueblo Viejo. The accurate samples provided by RC allow for improved stockpile and blending strategies, showing the importance of accurate samples to manage risk and create value, against the perception that savings can be made at the risk of poor sampling performance.CITATION:Almond, M and Ventura, L, 2017. Adding value with reverse circulation drilling at Pueblo Viejo, in Proceedings Tenth International Mining Geology Conference 2017, pp 277–284 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 20, 2017

Geological information plays a significant, cost effective role, in the Mt Whaleback iron ore mining operations. The geology and structure are complex. Good communication between the Mine Planning Production Scheduling and Quality Control Sections is the key to utilisation of geological information to its full potential.Drilling and pit face mapping are the two basic sources of detailed data sets which are processed to prepare up to date geological cross sections and benchwise geological plans. This information is used directly for the blast pattern design and production scheduling. Physical ore type estimation is also undertaken. Orebody models are generated from the geological information.

Jan 1, 1990

By Stewart R, Manson RA, Haig DW, Perembo RCB, Kruman B

Since the advent of plate tectonic modelling, the Ramu-Markham valley has been thought the site of a classical island-arc/conti- nent collision zone. In this interpretation the units south of the Markham Valley are held to be island are / micrcontinental mate- rial accreted to Australia and those north of the valley are thought to represent a separate Finisterre island-arc terrane. Recent remapping by the Geological Survey of Papua New Guinea shows: (1) there is no terrane boundary along the Ramu-Markham valley (2) the Finisterre Volcanics are probably part of either a fore-arc sequence or oceanic plateau obducted onto a microcontinent/ volcanic-arc composite terrane, accreted to the continental Australian plate. A new tectonic model is proposed for northern PNG and involves: (I) Eocene to Late Oligocene subduction below a microcontinent remote from Australia to produce the Sepik are and related intrusives, the Finisterre Volcanics (fore-arc or possible oce- anic plateau), together with the Alife blueschist. (2) obduction of the Sepik arc in Late Oligocene-Early Miocene times over the advancing Australian plate. This resulted in crustal melting, some of the products of which are the Mid- dle to Late Miocene Akuna and Bismarck intrusive complexes of the Maramuni arc. (3) obduction of the Finisterre Volcanics began in Early Pliocene times and continues today. (4) post-Middle Miocene mineralisation is the result of melting after obduction of the Sepik microcontinent.

Jan 1, 1997

By P B. Hills

A simple algebraic method of aligning large scale underground excavations such as a crusher station or workshop or indeed any large cavern or mine layout to the optimal stress condition is outlined. The method uses the stress transformation law to determine how the component stresses vary as the stress tensor is rotated around its axis. The aim is to define the orientations at which the maximum and minimum horizontal stresses occur such that the excavation can be aligned with its long axis paralleling the trend of the maximum horizontal stress leading to the minimum potential for overstressing of the side walls. The physical environment in which the stress field is acting is unchanged. At the design location, the trend and plunge of the major principal stress is unchanged. However, the coordinate system by which the location of the stress field is described is arbitrary and the stress transformation law allows that coordinate system to be rotated to a more convenient orientation and for the component stresses to be calculated within the alterative coordinate system. The stress field is typically described in terms of normal and shear stresses aligned to a north–south, east–west, vertical, coordinate system. In this scenario, there are two orientations in the 360° horizontal plane defined by the coordinate system where the horizontal normal stresses are equal, and at 45° to those orientations, two orientations where they diverge to the maximum extent. Those orientations of maximum divergence correspond to the trend of the maximum and minimum horizontal stresses, usually designated σH and σh, and that is what the algebraic manipulation seeks to determine. This technique is a first pass assessment which relies on a knowledge of the full stress tensor. It is not a replacement for numerical modelling or detailed design, but a tool to guide planning.

Nov 29, 2022

The Hunter Valley Rail Project (HVRP) represents most of the coal producers using the Hunter Valley Rail System in NSW to haul coal to the port of Newcastle. This system carries over 70 per cent of NSW's coal exports, comprising over 30 per cent of total Australian coal exports. Hunter Valley coal is the largest export industry in NSW, and one of its largest export growth opportunities. However, the industry is under intense pressure in international markets from existing and new coal producers and from other energy sources. Whilst potential growth in demand is substantial, particularly for thermal coal in Asia, excess world supply has pushed prices down, and this underlying trend may well continue. The industry has lost international competitiveness and as a result, investment has dropped 44 per cent over the last two years. The industry must be rapidly structured to compete and attract investment on the basis that these pressures will continue. Substantial productivity improvement and cost reductions must be made for the industry to regain competitiveness, otherwise growth will not occur and the industry will decline, with serious implications for the Australian and NSW communities. The introduction of internationally competitive rail freight rates is an urgent and essential part of this process. It is the key objective of the HVRP.

Jan 1, 1995

By P Guj, J A. Bell

The valuation of early-stage exploration projects requires a valuer to take into account a large number of uncertain value drivers, the interplay among which may be non-linear. This paper examines some of the key value drivers including geology, target metrics, project area and maturity, the market and the psychology behind the decision-making process. The commonly accepted valuation methods and their underlying logic are outlined, including a view on why they evolved, what value drivers they attempt to address and their potential shortcomings. These methods include the multiple of exploration expenditure, geoscience rating, expected values and market based methods. The potential future valuation methods of replacement values and neural networks are also introduced along with how to minimise heuristic bias and error within the market-based approach.CITATION:Bell, J A and Guj, P, 2012. Exploration value drivers and methodologies, in Proceedings Project Evaluation 2012 , pp 17-28 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 24, 2012

By Q Wang

Net present value (NPV) has been the main criterion in mining project evaluation and production plan optimisation. It is a common practice in NPV calculations to take into account only the tangible cost items in the corporate accounting system. The costs incurred due to damage to the local ecosystem and environment are left out and treated as externalities. Such practice on the one hand underestimates the total cost of a mining operation and, on the other hand, ignores the difference in ecological/environmental impacts between different mine plan alternatives. This paper attempts to measure the ecological costs of mining and to incorporate such costs into the evaluation scheme in mining project evaluation and mine planning. The ecological costs of mining are estimated based on the areas and types of land (eg forest land, grazing land, crop land) damaged by mining activities and the carbon emission from fossil fuel consumption. For the land areas (and their associated ecosystems) directly damaged by mining activities, the ecological costs are measured by the prevention and restoration costs, the lost values of eco-services of the damaged land, including bio-product production, soil erosion control, water run-off control, oxygen release, air pollutant absorption and formation of soil nutrients. The ecological cost of carbon emission from the energy consumption of a mining operation is measured by the cost of cultivating the equivalent forest land required to uptake the emitted carbon. A case study on a large-scale open pit mining project is presented to demonstrate the influence of ecological costs on the mine planning outcome.

Sep 26, 2011