Search Documents

By C M. MacRae

The characterisation of high-P iron ores by field emission gun electron probe microanalyser (FEGEPMA) was carried out to determine elemental associations in iron oxides sensus lato and, using this knowledge, to speculate on possible P incorporation mechanisms in goethite. Quantitative data was collected from two goethite-rich bulk ores and results showed that in both samples goethite was the main repository for phosphorus. The P-rich goethite also contained elevated levels of both aluminium and silicon.To understand the mechanism of P incorporation in goethite, high-P grains were located by coarse mapping of polished blocks with the FEG-EPMA. Analysis of element distribution maps collected on the P-rich grains showed that low-P regions within grains were typically associated with low-Al and high-Si, whereas high-P regions were associated with high-Al and low-Si. Based on follow-up quantitative analyses, a coupled substitution mechanism for phosphorus incorporation within goethite was proposed: 2Si4+ = 1P5+ + 1Al3+. Additional quantitative analyses on further examples indicated the mechanism was only valid for Si contents in goethite of <1 wt per cent.Preliminary transmission electron microscope (TEM) studies confirmed the presence of P, Al and Si in goethite.

Jul 11, 2011

By Bunting HR

Developments since 1959 in major excavators to meet the high outputs of overburden and coal under the changing nature of the Morwell Coal Deposits of the Latrobe Valley are described. Particular reference is made to investigations of designs of the bucket wheel head configurations for the digging of flat batters on high faces, and examples are given of the wide use ofmodelsin these studies.An explanation is given of considerations leading to selection of the Long Boom or the Compact type of bucket wheel excavator for various applications. The past decade has seen increasing manufacture in Australia of components for excavators and similar machines. The measures undertaken to integrate these components with those from overseas (Germany) are described. A section of the paper deals with advances in Electrical Engineering for large excavators in Australia and its interdependenee with mechanical design and construction. Finally, as an example of the versatility of the bucket wheel excavator a description is given of a recent application for the mining of mineral sands in Northern N.S.W.

Jan 1, 1970

Five Hypotheses are given for factors influencing long-run metals price forecasts. 1 . Geologists succeed when given the money. 2. Better understanding of a metals market depresses its price. 3 . Statistical techniques get forecasts wrong. 4. Long-run metals prices are related to crustal abundance. 5 . Economic cycles affect metals prices more than is realised. These are then framed within the transition between eras as influenced by apparent long waves in economic activity. Innovation surges during the transition between eras. The transition to the 5th Wave since the Indus- trial Revolution 200 years ago is now underway. Finally, price projec- tions are given both for the 5th Wave and 200 years from now on the assumption that a similar monetary measure to today will be then extant.

Jan 1, 1988

Quantitative probabilistic ecological risk assessment has been used to evaluate the likely effect on fish diversity and abundance of filtered and bioavailable metals in streamwater affected by acid drainage from the abandoned and remediated Rum Jungle U/Cu mine in the Northern Territory of Australia. The water quality was determined using monitoring data from a gauging station on the East Branch of the Finniss River, downstream of the mine site, and modelled assuming a number of potential water quality management options. The management options ranged from no action, through some flushing options to full catch and treatment of contaminated seepage from the waste rock heaps. The computer code AQUARISK was used to undertake the analyses. Critical criteria for contaminant water concentrations at the site, derived from probability density functions of available fish ecotoxicology data, were found to closely approximate the regulatory trigger values for the contaminants of concern. Modelled predictions of reduced diversity and abundance were also in good agreement with in situ biodiversity measures. Based on a reasonable target of 67 per cent species tolerance for this heavy impacted site, it was found that none of the low cost options for wastewater management was acceptable. Combinations of two of the options approached acceptability. Both of the catch and treat options exceeded the arbitrary acceptability target well. This implied that the more expensive option of liming to pH 10 might be unnecessary at this site. Thus, the use of ecological risk assessment modelling has proven useful in undertaking cost-benefit analyses for this site. The approach provides a management decision-making tool that can be economically used to link expensive on-site environmental engineering options with site-specific ecological goals rather than the previous nebulous aims of æreduced contaminant loadÆ or æimproved biodiversityÆ that often resulted in excessive expenditure without achieving successful environmental benefit.

Jan 1, 2003

By R W. Henley, L Knuefing, M Turner, Y Zhang, M Saadatfar, A Limaye, R Cruikshank, M A. Knackstedt, A Kingston, L Beeching, N Francois

A better understanding of ore fragmentation and the textural features of ore is a key to the energy efficient extraction of targeted minerals from low-grade ore deposits. In this study, X-ray microcomputed tomography (micro-CT) is employed to study mineral liberation during the tensile failure and onset of fragmentation of a copper ore. Our results show that X-ray micro-CT could inform new studies of ore micromechanics and fragmentation at the laboratory scale and may offer new avenues to address current challenges in the design of efficient comminution processes. We present the results of experiments based on a high-pressure apparatus enabling micromechanical studies to be carried out in situ (inside a micro-CT scanner). This platform produces high-quality 3D images of the evolution of a sample of porphyry copper ore during an in situ fragmentation test. A sequence of tomographic images enables mapping in 3D of both the deformation of mineral phases and the fragmentation process. The fragmentation occurs quasistatically through multiple stages starting with an initial tensile fracture splitting the ore diametrically, followed by tensile-activated nucleation and growth of multiple fractures producing a complex fracture network. Coupling breakage with microstructural information enables quantitative determination of the impact of ore texture heterogeneity on fracture patterns and mineral liberation. This microstructural information can be compared to key measurements of the ore mechanical behaviour such as the global deformation energy, strain deformation field and the stress relaxation response. The latter allows one to identify interesting precursor signals of the tensile failure. The copper liberation, fragment size distribution and breakage patterns are statistically characterised and related to comminution mechanisms which are clearly identified in the sequence of tomographic images. The two dominant mechanisms are rock-rock friction/compression induced by fracture closing and compression-driven fragmentation at rock-crusher contact points.

Aug 24, 2022

By Pratt V

The economic, social and political environment of the mining and minerals industries is, as we all know, volatile and affected by constantly changing international forces. In addition, the outcome of negotiations with overseas customers is often uncertain for long periods, or even unfavourable. The industries and companies represented at this Conference are in an arena of high competition, risk taking and enormous capital outlay. They are industries which our overseas markets (rightly or wrongly) have criticised for industrial relations problems, unreliable production and uncertain deliveries. They are industries which have an urgent need to be cost effective and competitive at all levels of activity.A critical factor in the mining and metallurgy industries is, therefore, its human resources and its human resource management. It requires the full use of available talent, innovation, skills and qualifications within its workforce, and the appropriate management of these resources.

Jan 1, 1985

By K L. Avarmaa, M A. Rhamdhani, A D. P Putera, H T. B M Petrus, G A. Brooks

Multistage slag treatment was carried out to investigate boron removal from metallurgical grade silicon. Boron is known to be one of the most difficult elements to remove from silicon. Depending on boron initial concentration, boron can be removed from silicon into certain level; most previous studies have attained final 50–100 ppmw (parts per million weight) boron in the silicon using slag treatment. The term ‘multistage’ refers to a process where the resulting silicon from the initial slag treatment is further refined multiple times using a new slag. In this study, an initial slag composition of 45CaO-45SiO2-10Al2O3 (wt per cent) was utilised. Using this technique, boron level in the silicon was expected to be gradually lowered because the new slag will always have more capacity to reach the equilibrium distribution coefficient (LB = (ppmwB)slag/(ppmwB)Si). The current study was carried out through combined thermodynamic calculations (using FactSage™ ver 8.2, by Thermfact Ltd, thermochemical package) and high-temperature experimentation. The thermodynamic calculations were carried out for reactions at 1500, 1550, and 1600°C for three different scenarios: 1. Single stage refining with varied slag to Si ratio. 2. Multistage refining with slag to Si ratio of 1:1. 3. Multistage refining with slag to Si ratio of 2:1. The multistage experimental work was carried out at 1550°C under inert gas atmosphere each time for 2 hrs, with slag to Si ratio of 2:1. The simulation results indicate that the boron distribution coefficient stay essentially constant with varying slag to Si ratio and temperature, around 1.8 to 2, and the experimental results measured LB in the same range, between 1.5 and 2.5. By harnessing this feature, the simulation showed that boron can be removed by approximately 78 per cent in each stage. The experimental result confirmed that the boron concentration in the silicon was reduced by a total of 97.8 per cent from its initial value using four stages of slag treatment, from initial 270 ppmw down to 6 ppmw.

Aug 21, 2024

By J Zhou, D M. Hunter, S M. Iveson, K P. Galvin

The recovery and concentration of ultra-fine iron ore can provide significant economic benefits. Presently, there are limited options available given the low settling rates achieved by conventional gravity separation and the relatively poor performance of reverse flotation. The Reflux Classifier is a new water-based gravity separation technology that consists of a set of parallel inclined channels positioned above a vertical fluidised section. This arrangement promotes a powerful throughput advantage compared to conventional fluidisation and a highly selective hydrodynamic basis for achieving sharp separations. A high shear rate develops within the inclined channels, which generates sufficient hydrodynamic lift to convey the lower-density particles (even if they are relatively coarse) to overflow while retaining the high-density particles (even those that are ultra-fine) for discharge to the underflow. The technology has previously been used around the world on particle sizes in excess of 0.1 mm. The present work, however, is concerned with density-based separations down to much finer particle sizes approaching 0.01 mm.A major advantage of the Reflux Classifier technology is the achievement of simultaneous gravity separation and desliming via a single-stage separation. A series of continuous experiments was conducted using an iron ore feed with head grade of 35 wt per cent FeT and nominal top size of 0.106 mm, with 59 wt per cent being below 0.038 mm in size. At a low throughput of 1.5 t/(m2 h), the Reflux Classifier produced high-grade products at a high recovery. For the entire feed, grades of 66.1 wt per cent FeT with Fe recoveries of 80 per cent were achieved in a single-stage separation. Within the 0.020–0.038 mm size fraction, grades of 68.8 per cent were achieved with iron recoveries of 94.7 per cent. Excellent recoveries of up to 57.0 per cent were achieved for the -0.020 mm size fraction. The ability of the inclined channels to retain the fine dense material further enhances the effectiveness of the Reflux Classifier by creating an autogenous dense medium effect within the vertical section. This helps to elevate large gangue particles up into the overflow.CITATION:Hunter, D M, Zhou, J, Iveson, S M and Galvin, K P, 2015. Gravity separation of ultra-fine iron ore in the reflux classifier, in Proceedings Iron Ore 2015, pp 143–148 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

The Ramu chromite deposit occurs in the Marum Ophiolite complex and is the most economically attractive chrom-ite deposit in Papua New Guinea. Its lateritic nickel, chromite and cobalt potential has attracted several compan-ies to prospect the deposit.In the present work, the compositions of chromite in the Ramu lateritic deposit and coexisting olivine-chromite pairs in Marum Ophiolite dunite were analysed with the electron microprobe for Fe, Mg, Cr and Al. The results were used to determine the relationship between the cations in the tetrahedral and octahedral structures of the chromite. In addition, the Fe, Mg, Cr and Al cations of the coexisting olivine-chromite pairs were used to calculate the equilibrated temperatures of crystallisation of the chromite. The variation of Fe", Mg and Cr cation values of the chromite in relation to the calculated temperatures was studied by regression analysis.

Jan 1, 1994

By Lukaszewski GM

The indiscriminate surface disposal of coal waste in the past has created a serious fire hazard in the bush of the northern New South Wales coalfields. Spontaneous or bushfire-induced combustion in large neglected dumps of this material has increased in recent years causing a rise in air pollution. Surface methods of coal waste disposal are still being practised, and in many cases new material is being added to old dumps, many of which are burning. CSI RO has conducted research on methods of preventing and controlling fires in coal waste and recommends practical methods of overcoming these problems. Some laboratory and on-site investigations are described and the hazards of improperly constructed dumps are considered. The available techniques of fire prevention and control are discussed in relation to Australian conditions. Proposals for the safe and economical disposal of coal waste are outlined.

Jan 1, 1970

By Blockley J. G, Laeter J. R

The history of the Ph-Cu-Zn mineralisation in the orthampton Block of Western Australia has been further investigated. It was hoped that (1) Rh-Sr studies on partially-remelled granulites, wall-rocks to the dolerite dykes, should date the dolerite intrusion, (2) Rh-Sr data on hydrothermally-altered dolerite should date the sulphide mineralisation, (3) Pb model ages on the galenas might provide an independent dating of the mineralisation, in addition to any geochemical information that might be derived. Only the second dating aim was fulfilled, but the Pb isotope data, when combined with the Rh-Sr data, have permitted deductions about U, Th and Pb abundance changes during the regional metamorphism, and about a possible source of the ore Pb. In detail the following has been found. (1) The partially-remelted granulitic wall rocks yield a scattered whole-rock Rh-Sr isochron which seems not to have been reset by the dyke intrusion (age 1037 ± 146 Ma, with initial Sr ratio 0.7171 ± 0·0054, MSWD = 111). This date agrees well with that reported previously for granulites from another locality; together theyestablish the time the metamorphic period closed. (2) The hydrothermally-altered dolerites yield a Rh-Sr whole-rock date 434 ± 16 Ma, with initial Sr ratio 0.7072 ± 0·0029 and MSWD = 31, taken as referring to the time of Ph-Zn mineralisation. This contrasts with a report of much older palaeomagnetic and K-Ar datings of the dolerite (not less than 550 Ma, possibly older) and suggests that neither the dolerites nor their heat have had any connection with the mobilisation of the Pbscavenging solutions. (3) The Pb isotope ratios of galenas from the ores yield a well-correlated regression which is not amenable to any of the model-age calculations. (4) The Pb-isotopic trends negate any genetic connection between dolerite and mineralisation, but the country-rock granulites could be the Pb source. (5) Combination of the Rh-Sr dates and the Pb data in a "simultaneous isochrons" construct permits the inference of major losses from the system during the regional metamorphism, in the order U>Pb>Th, with substantial homogenisation of the remaining Pb. This left a wide range in local UlPb and Th/U among the source rocks which eventually were scavenged by the mineralising solutions. (6) These geochemical deductions are shown to be compatible with previously-published information on the abundance ofU and Th in the Northampton Block granulites, which are thus seen to be credible as source rocks for the ore lead.

Jan 1, 1985

In May 1977 a new dam was commissioned for disposal of 600,000 metric tonnes/year of tailings. Design basis, costs and construction problems are described. Problems arose, assoc- iated with lack of experience in building such a dam "from scratch". Solutions are described land costs given.

Jan 1, 1978

By E Villaescusa, C Drover

The stability of access tunnels is one of the main engineering challenges in deep underground mine construction. Many underground hard rock mining operations are now reaching depths where the induced stresses are such that sudden and violent failure of the excavations can occur very soon after construction. The loading conditions on the installed ground support schemes are often underestimated by conventional engineering design methods. Therefore, the actual loading conditions often exceed the installed ground support capacity. This can result in failure of the excavations and, in extreme cases, potentially closure of mining operations amounting to hundreds of millions of dollars in lost production. More frequently, violent excavation instability at great depth causes operational delays, costly and unplanned rehabilitation, as well as risks to worker safety. In order to address this challenge, this paper briefly summarises a modern, innovative approach to the design and construction of mine development at great depth. The process follows seven main steps. The first step is to characterise the rock mass strength, structure and stress. The second step is a stability assessment, which identifies the plausible modes of excavation failure, based on the rock mass characterisation. The third step is the definition of an excavation geometry which is harmonic to the high stress conditions. The fourth step is to prepare a site-specific face destressing drill and blast design which will reduce the potential for rock mass instability during the development construction cycle. The fifth step is to accurately quantify the expected loading conditions on the installed ground support. The method of doing so is uniquely analytical and probabilistic. It is based on the natural mechanical relationships between rock strength, structure, induced stress and the physical characteristics of the instability, including its mass and ejection velocity. The sixth step of the design process is to specify a ground support scheme arrangement with sufficient strength and displacement capacity to exceed the rock mass demand by a safe margin. The final stage is to install the complete ground support scheme using mechanised technologies which minimise the exposure of the equipment operators to unsupported ground at the tunnel face.

Nov 29, 2022

By Brumley J

The development of the SECV brown coal open cut at Loy Yang will require depressurisation of aquifers both within and below the coal seam sequence in order to maintain open cut stability. Prediction of future open cut dewatering requirements at Loy Yang Open Cut and evaluation of the regional consequences of dewatering has required development of a detailed hydrogeological model of the Loy Yang area. The complex stratigraphy of the coal seam and aquifer/aquitard sequences at Loy Yang have been analysed and integrated with the hydrogeological concepts developed from regional groundwater studies to formulate a realistic hydrogeological model as a basis for finite-element flow modelling.

Jan 1, 1988

By Cocks T

The 15-year long debate between the industry, Government and Aboriginal people about the rights and wrongs of Land Rights, the right of Aboriginal people to control development on their land and the relationship between the parties, has been long and often bitter. It has so far been a war of words and often the truth has been the first casualty. This paper looks at the debate and presents the perspective of Aboriginal people, as well as looking at how the industry and Aboriginal people can work together for everyone's benefit. It addresses such matters as: ò why Aboriginal people believe they have the right to control development on their land; ò the perception that Aboriginal people are anti-development; ò the perception that Aboriginal land is 'locked-up'; and ò how companies can negotiate with Aboriginal people.

Jan 1, 1994

By McCarthy P. L

A distinctive feature of the goldfields of Victoria was the extrac- tion of gold from deep leads, that is the buried river beds of Vic- toria's ancient rivers and streams. It is estimated that about 265,000 kg of gold was produced from Victoria's deep lead mines which comprises about 11.5% of Victoria's total production of gold (Bowen, 1974). The significance of deep lead mining for Victoria, however, went far beyond its economic contribution to Victoria. If Profes- sor Blainey is correct it was the frustrations of mining gold from deep alluvial leads in Ballarat during 1854 which precipitated the Eureka Stockade (Blainey, 1963, 46-52). This event resulted in the implementation of a fair mining administration and was an emphatic statement of the rise of democratic movements in Australia. Much of the technology and skill for mining deep leads had to be developed locally because at that time no other major gold- field elsewhere in Australia or the world had gold deposits with comparable problems. Deep lead mining in Victoria was there- fore largely a home grown industry and the equipment for that industry was often designed and produced in Victoria.

Jan 1, 1988

The treatment of the Broken Hill ores has,undergone many changes during the last ten years, and it may be of interest to some of the members to know what are the main lines on which the Proprietary Mine works at present. It must be understood that the want of absolute uniformity in the treatment amongst the various mines at the Barrier does not prove that some of the mines are working on wrong lines, for the ore is not exactly the same along the whole line of lode; this necessitates a variation in treatment, although generally only in detail.At the Proprietary Mine the ore is all mined by contract the miners are paid so much per ton for clean ore. The ore in the mine in most stopes is mixed with gangue, and the inclination of the uliners is, of course, to mix gangue with the ore, so as to be paid for as large 3 tonnage as possible. This is quite natural clean ore is easily distinguishable from clean gangue, but most lumps are a mixture of clean ore and gangue in varying proportions. The miner will naturally throw into his heap pieces which he considers still good enough, whilst the management may consider these pieces just a trifle too poor; consequently a check must be kept on this.This necessitates the first operation to which the ore is submitted. 'The trucks tare 51 cwt.; average load 21 cwt.), as they are loaded underground, have a ticket attached::showing to whiyh contract they belong on arrival at the top of the shaft they are passed over a weigh bridge...

Jan 1, 1907

By B M. H Sharp, R P. Hide, S P. Devine

Uncertainty and debate currently pervade the mining industry in New Zealand. The operational uncertainties, whether external (eg gold prices, the exchange rate), or internal (eg coal expansion difficulties), are large. In addition, many wider factors which influence mining are in a state of flux. State Coal Mines, the operating branch of the Mines Division of the Ministry of Energy I may be made a state corporation, with the remaining Mines Division functions being revamped. The agencies administering environmental legislation are to be restructured. Mining legislation amendments have been proposed and then dropped, and the area is now to be reviewed (The Press, 31 July 1985). Some mining licences have been withdrawn, and become the subject of heated debate in the community (The Press, 19 July 1985, and subsequent letters to the editor).

Jan 1, 1985

By Nicol SK, Engel MD

Ion flotation involves the adsorption of ionic species, in association with surfactant molecules, at the surface of rising gas bubbles, for the purpose of recovering and concentrating those ions. The objective of this study was to optimise the ion flotation process using a heap-leach liquor, containing gold cyanide, and the surfactant cetyl trimethyl ammonium bromide (CTAB). The aim was to minimise the surfactant reagent dose, maximise the throughput of feed liquor in the process, and satisfy the dual constraints of a high gold recovery and a high volume reduction factor. Development of a first order model of the ion flotation process formed the theoretical basis for the test program procedure and the interpretation of the results. Batch tests were used in order to determine the ultimate recovery curve for the heap leach liquor-CTAB surfactant system. The results indicated that a surfactant dose of about 0.083 g/l would be necessary in order to achieve a satisfactory gold recovery. Continuous tests were then performed on a small-scale pilot plant at the Newcastle Laboratories. The optimum result achieved was a gold recovery of 85 per cent, a volume reduction factor of ten, and a feed throughput of 2.3 m3/m2-h. Recent work also indicates that very much higher volume reductions can be achieved using a larger diameter vessel. The improvement may be a consequence of a reduction in wall effects and hence an improvement in foam drainage.

Jan 1, 1993

By Aziz N

The objective of the paper is to develop an understanding of the influence of caving on powered support rating by examining the geology and support performance at two sites which represent the current extremes in support rating, ie 6/240 Ton supports operating in the Hirst Seam at Solsgirth Colliery, Scotland, and 4/900 Tonne supports operating in the Bulli Seam, West Cliff Colliery, Australia. A conceptual model is introduced which considers the coal ahead of the face, the powered support, and the caved waste to be three yielding foundations which interact to control the subsidence of the roof strata. Different caving mechanisms are identified for the strata of the Hirst and Bulli Seams, ihese mechanisms being related to rock properties, ie to the palaeogeography and depositional conditions at each site, producing caved wastes with different yield characteristics. The results obtained for convergence and support reaction during production cycles at both sites are analysed to show the manner in which support reaction is developed, indicating the importance of high setting load densities in the Bulli Seam. Evaluation of the work done on the subsiding roof strata during typical production cycles by two of the yielding foundations, ie the powered support and the caved waste immediately behind the powered support, is used to further demonstrate the influence of caving mechanisms on support rating.

Jan 1, 1986