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By S Basu, P M. Midhun

Electro-Slag Remelting (ESR) is a process capable of producing ingots with much lower centre-line segregation and better internal soundness than conventional ingot casting processes, as well as lower inclusion and sulfur concentrations. This process is commonly used for alloyed steels intended for critical applications like components of marine turbines, supercritical powerplants and rocket motor casings. It involves melting a metal electrode using electrical resistive heating in a slag pool and re-solidification of the resulting metal droplets beneath the slag layer, forming an ingot. Conventional ESR fluxes consist primarily of CaF2, Al2O3 and CaO, along with minor concentrations of SiO2, MgO etc. The emission of fluoride vapour from the molten slag causes several environmental and health problems, triggering a need to develop and reduce the fluoride content in the ESR flux. The present study aims to develop low-CaF2 alternatives to commercial ESR fluxes without compromising on productivity and the surface quality of the refined ingot. Thus, the modification in chemical composition needs to satisfy properties like electrical resistivity, viscosity and liquidus temperature, essential for efficient ESR operation. Since electrical resistivity and viscosity are highly dependent on the ionic structure of the molten slag, it is important to understand the effect of compositional modification on the structure of the flux. The present study employs Fourier-transform infrared spectroscopy (FT-IR) and Raman spectroscopy to investigate the structural variations in the modified fluxes, especially the effect of changing SiO2 concentration, in comparison with conventional CaF2-rich fluxes. Additionally, thermal analysis (Differential Thermal Analysis (DTA) and Thermogravimetric Analysis (TGA)) has been carried out to characterise the melting behaviour of the fluxes. The findings are compared with simulations carried out using the FactSage™ software, ver 8.3 (GTT Technologies, Aachen, Germany). Simultaneous analysis of liquidus temperature and the structure is expected to help in identifying the practical suitability of modified ESR flux compositions for industrial implementation.

Jun 19, 2024

By Y Mita, T Iwama, R Inoue, S Ueda

In the iron and steel manufacturing industries, efforts are being made to achieve carbon neutrality by 2050, and the transition from a coal-based steelmaking process to that utilising renewable energy is being pursued. An alternative process in which directly hydrogen-reduced iron is melted in an electric furnace is being investigated. It is known that foaming slag reduces heat loss from the steel bath in electric arc furnace, but iron loss due to the suspension of steel particles in the slag is indispensable. To improve the separation of steel particles from the slag, the control of the slag viscosity is important. Although the slag viscosity has been extensively studied, in those studies the slag was considered to be a simple liquid. However, in actual operations, slag is a multiphase fluid consisting of solid, gas and liquid phases. Therefore, in this study, by measuring the sedimentation velocity of titanium, stainless steel and glass spheres in an aqueous glycerin solution containing bubbles generated by the reaction between NaHCO3 and C2H2O4, the apparent viscosity of the gas-liquid fluid was evaluated based on Stoke’s law. It was found that the apparent viscosity of the gas-liquid fluid is larger than the viscosity of liquid phase and depends on both the bubble volume ratio in solution and the density of the falling solid sphere, and the apparent viscosity was different from that previously obtained by the rotation method. The apparent viscosity derived from the sedimentation velocity of solid spheres changed depending on the specific gravity of the ball. This is because the apparent viscosity is derived from the velocity of a ball falling in a static bubble in this method, whereas that is derived from the force applied by a stationary flow in the rotational method.

Aug 21, 2024

China has been producing gold for more than 4000 years with gold production increasing substantially since the 1980s, from about 25 tonnes in 1980 to some 160 tonnes in 1998. More than 80 per cent of the gold production is from East China. However, complete information on eastern China gold has been rarely reported internationally. This is a general overview on the tectonics and metallogeny of gold deposits in East China. The geology of these gold deposits is compiled mainly from data and information reported in China, and is also based on the authorÆs work in China from 1974 to 1986 and a recent visit to China.

Jan 1, 1999

By D J. Williams, M S. Zbik, A Shokouhi

There is a considerable difference in the particle size distribution (PSD) of clay mineral-rich coarse coal reject with variations in the test moisture state and the chemistry of the water used for testing. The coarse coal reject tested were collected from Jeebropilly Mine, located in the Ipswich Coalfields of south-eastern Queensland. Differences between the results of dry and wet sieving analysis indicate a significant breakdown of the clay mineral-rich coarse coal reject on wetting-up. Wet sieving caused a breakdown of the gravel-sized fraction to silt and clay size without significant breakdown to sand size. There is also a considerable variation in the results of hydrometer analyses of the clay mineral-rich coarse coal reject with variations in the chemistry of the water used, particularly at the fine end of the particle size range. The waters used included tap water, coal processing water and deionised water. In addition, the method of dispersion applied prior to hydrometer analysis can have a significant effect on the PSD of clay mineral-rich coarse coal reject, with boiling and sonic vibration causing the most breakdown of the clay particles. This paper describes the testing methodology used and the test results obtained, and attempts to explain the results in terms of clay mineralogy and water chemistry.CITATION:Shokouhi, A, Williams, D J and Zbik, M S, 2015. Influence of water on particle size distribution of clay mineral-rich coarse coal reject, in Proceedings Tailings and Mine Waste Management for the 21st Century , pp 239–246 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 27, 2015

By Boland J

Prediction of rock cuttability by various excavation machines such as tunnel boring machines, road headers, rippers, picks, roller disc cutters, excavators, etc is of major concern to both civil and mining engineers and rock mechanics. In principle, the design of a rock cutting tool is based on achieving maximum excavation with minimum input energy, minimum applied force, minimum equipment weight and volume and, more importantly, minimum tool wear. When a rock material is indented by the force of a cutting tool and then unloaded several material zones form underneath and around the tool. As the tool moves into the rock the volume of its associated rock cavity (ie volume of displaced rock) expands and depending on the indenter's shape various phenomena may occur. Immediately beneath the tool a small zone in which the stress state is more or less hydrostatic, is formed which is underlain by an inelastic, or damaged, material zone. Both size and shape of this damaged zone control the magnitude of the indentation force and the chip formation mechanism during unloading. The rock is unable to store the whole strain energy induced by the tool and consequently the extra energy is expended either in forming new fracture surfaces and/or in plastic deformation in the damaged zone. Therefore, it is not surprising to see that both perfect-elastic and rigid-plastic constitutive models are not generally suitable for modelling indentation of rocks. In contrast elastoplastic constitutive models are more appropriate as they can include both elastic and plastic deformations (Kral et al, 1993). Elastic solutions for several half-space indentation problems can be found in most text books on elasticity and in particular in Timoshenko and Goodier (1951), Sneddon, (1951), Poulos and Davis (1974) and Johnson (1985a). If a failure criterion, eg the Mohr-Coulomb failure criterion, is applied to delimit elastic solutions for indentation problems, a lower bound limit of the applied indentation force (for a given indentation depth) can be estimated. It may be noted that elastic analyses, without any delimiting failure criteria, normally overestimate the indentation force. Plastic solutions for a few indentation problems may be found in Hill (1950), Johnson, (1985a) and Alehossein et al (1992). When analysing the behaviour of indented rocks the choice of an appropriate constitutive model describing effectively the behaviour of the rock at various stages and phases during indentation is a challenging issue. Several questions need to be answered before starting an effective analysis. The first question is of course: Which one of these is more appropriate for modelling zones underneath and around a cutter, elasticity or plasticity theory, continuum damage mechanics or fracture mechanics, and what is the bridging link between these various theories? Which mode is more dominant in fracturing rock, tensile or shear mode? What governs the mechanism of chip formation? What is the function, shape and the behaviour of the pulverised zone that forms just underneath a cutter? Is the hydrostatic stress state assumption reasonable for this zone? How does the rock change during the absorption and dissipation of the input energy and how does the indentation energy vary with rock type and depth of penetration? How can we model the damaged zone under the indenter? Furthermore does a plastic material form beneath the pulverised zone? When and how do radial and ring cracks form around and under an indenter?

Jan 1, 1995

By Y Li, B Shen, S Zhang

Jointed rock mass is often encountered in rock engineering and its stability has always been a major concern in underground engineering. To analyze the stress characteristics and their variations in jointed rocks, in this study, a new concept of sub-instability stage before rock failure is defined, and a new experimental method is used to investigate interaction between defects and intact rock of the jointed rock mass during the subinstability stage., Firstly, external characteristics of stress and failure mode of the whole jointed rock are investigated systematically by conducting uniaxial compression tests on red sandstone samples with a set of preexisting open flaws of different sizes, and the interactive damage of intact parts and defects in the subinstability stage was further studied. Secondly, rock-like material samples made of bonded plaster blocks were tested and internal data from stress sensor between the strong and weak segments were collected. The transforming processes from independent activity of the individual segment to overall interactive movement of jointed rock before the unstable failure were analysed. The test results indicated that the subinstability stage marked the beginning of interactive failure between the intact rock and defects. In the early subinstability stage, the relatively intact parts bore most of the load in a jointed rock mass, and the defects were damaged firstly which caused high strain around it. The areas of high strain increase rapidly, extending and migrating, causing damage to the intact parts. In the later sub-instability stage, the interaction effect reached its maximum, and a large number of cracks appeared in the intact rock and they propagated and coalesced. Intact parts experienced rapid failure and then the jointed rock failed. The experimental method used in this paper to identify the sub-instability stage could be used to identify failure precursors of jointed rock masses and to develop technology for disaster prevention in rock engineering. CITATION:Zhang, S, Shen, B and Li, Y, 2018. Experimental studies on interactive failure characteristics of jointed rock, in Proceedings The Fourth Australasian Ground Control in Mining Conference (AusRock), pp 453–461 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 30, 2018

By Andrews B. S

The sinter plant at the Sulphide Corporation's Cockle Creek works produces a feed for the company's Imperial Smelting Furnace. The feed contains lead and zinc oxides and all the fluxes necessary for furnace operation. The quality of this feed is a major factor in furnace performance and the considerable flexibility of operation possible at the sinter plant has been used in efforts to achieve optimum operating conditions.Operating data is processed daily and information gathered from this source has led to three of the four improvements described.These improvements have resulted from elimination of gas recirculation, reduction of sinter returns sizing and alteration of ignition conditions and main layer fuel loading.

Jan 1, 1964

By T QUINLAN

A resource estimate uses data obtained by sampling an orebody. An example is described in which a random drilling pattern did not provide a representative set of assays, and the estimated resource was significantly less than the mine production. It is believed that a better estimate would have been made if the exploration holes had been drilled on a regular grid.

Jan 1, 1992

By M Manefield, G Bournival, S Ata

Asteroids contain an abundance of valuable resources such as: nickel, cobalt, gold, platinum and rhodium. Whilst the consumption of mineral resources on Earth continues to deplete, meteoroids have the potential to become a significant source of minerals. Even though the minerals content of asteroids may be relatively high, the valuable minerals are more likely to be only a small portion of the total ore present in the main body. The ores must, therefore, be processed to extract the metals of interest from the waste. Existing terrestrial technologies rely on manipulating the physical and chemical properties of minerals. The application of these techniques to asteroids processing, however, is not straightforward due to the presence of different conditions such as zero gravity and lack of water in space. This paper discusses potential separation and extraction techniques that can be used for processing of asteroids.CITATION:Ata, S, Bournival, G and Manefield, M, 2015. Resource recovery in space, in Proceedings Third International Future Mining Conference, pp 275–280 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 4, 2015

By R Dimitrakopoulos, I Minniakhmetov

Geostatistical simulation techniques are used to quantify uncertainty of spatial attributes of interest describing mineral deposits, petroleum reservoirs, hydrogeological horizons, environmental contaminants and so on. The majority of existing methods consider second-order spatial statistics and Gaussian processes, while the more advanced multiple point-based simulation approaches are algorithmic and do not consistently account for the high-order spatial relations in data. Recently, simulation techniques for complex and non-Gaussian spatially distributed variables have been developed, based on high-order spatial cumulants, and make no assumptions on data distribution or require data transformations. In this paper, the previous developments are extended and a new approach for the joint simulation of multiple correlated variables using high-order spatial statistics is proposed. The technique is based on a new algorithm for the decorrelation of correlated variables into factors, using the so-termed diagonal domination condition of high-order cumulants. The decorrelated factors are then simulated using high-order simulation and back-transformed into the initial correlated variables. The decorrelation using diagonal domination of high-order statistics is tested with a data set from a multielement iron ore deposit, and then a fully known two-dimensional data set with two correlated variables is used to demonstrate the practical intricacies of the proposed method.CITATION:Minniakhmetov, I and Dimitrakopoulos, R, 2014. Joint simulation of correlated variables using high-order spatial statistics for orebody modelling, in Proceedings Orebody Modelling and Strategic Mine Planning Symposium 2014 , pp 53–60 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 24, 2014

By Manca PP, Lassandro R, Caranassios A, Massacci G, Ciccu R

The paper discusses the state of the progress reached in the development of the diamond wire tool for cutting hard rocks. To the advances of this relatively new technology a substantial contribution has been provided by the research being carried out at the University of Cagliari on samples of granite rocks from different Sardinian stone quarries. On the basis of field experiments and laboratory test data, the mechanism of diamond wire cutting has been assessed. In particular the influence of the rock features and operational variables on tool performance (cutting rate and bead wear) has been Elucidated.

Jan 1, 1992

By Johnson N. W, Manlapig E. V, Alexander D. J, Franzidis J. P

The importance of the froth region on flotation performance is often emphasised in the literature. It is well-known that decreasing froth depth or increasing air flowrate results in increasing cell recovery at the cost of lower concentrate gra

Jan 1, 1997

Low-grade, porphyry copper type mineralization at the Moonmera prospect is related to the intrusion of a granodiorite porphyry mass into the Upper Permian "Gracemere granodiorite". Significant copper mineraliza- tion appears to be associated with the alteration assemblage quartz-sericite- kaolinite. The ore shell is surrounded by a zone where montmorillonite and kaolinite are in greater abundance and this assemblage is over- lapped, mainly at depth, by potassium feldspar alteration. Secondary biotite is abundant throughout the mineralized zone. Preliminary sulphur isotope results on the sulphide mineralization are compatible with a magmatic origin for the sulphur.

Jan 1, 1974

Current models for the origin of banded iron-formation (BIF) derived in situ iron ore deposits assume that the typical chert and iron oxide banded BIF is the primary rock from which enriched iron ore deposits arise by the selective leaching of quartz and the residual accumulation of the iron oxides. Weathering extends to the base of all the hematite deposits of the Hamersley Province, which lie within the saprolitic weathering zone, as shown by the preservation of the primary textures, and are overlain by a hydrated goethite zone representing the solum. Since groundwater typically contains dissolved silica, derived from the hydrolysis of silicate minerals, greatly in excess of the saturation solubility of quartz, it is incapable of removing quartz from below the watertable, and quartz is preserved in all saprolites derived from quartz bearing rocks. Quartz may be dissolved in the solum due to the influx of meteoric water having little or no dissolved silica, but soil-forming processes that dissolve quartz likewise alter the oxides by hydration and transposition with consequent destruction of primary textures, and there is no suggestion of soil-forming processes having produced the deposits, which typically extend to considerable depths below the water-table. A characteristic feature of the typical hematite orebodies is the unaltered nature of the iron oxides in the ore compared to those in the adjacent cherty BIF. Although the solubility of ferric iron at >10 ppb is much less than quartz, any process capable of dissolving the huge volume of quartz must also affect the iron oxides, but evidence of this is completely lacking in most ore deposits. Hydrothermal alteration at Koolyanobbing in the Southern Cross Province affects both cherty BIF and ore, and clearly shows equal mobilisation and recrystallisation of hematite within quartz/hematite veins and in the surrounding cherty BIF, which shows no evidence for the selective leaching of quartz. Similarly, any metamorphic process capable of removing all quartz from BIF would leave characteristic evidence in the remaining oxides. However, a hydrothermal process may account for at least portions of certain ore deposits, in which the chert bands have been replaced by carbonates at comparatively low temperatures, to produce a quartz-free magnetite/ carbonate rock that is readily upgraded to high-grade ore by supergene dissolution of the carbonates. This process is interpreted to have formed high grade ore at Mt Gibson, Koolyanobbing æAÆ Deposit and Mt Tom Price North Deposit. In addition to carbonate replaced cherty BIF at Mt Gibson in the Murchison Province, there are extensive sequences of magnetite BIF without chert bands, and this chert-free facies of BIF is interpreted as the precursor to the majority of in situ hematite ore deposits, through oxidation and weathering of magnetite and iron silicate and carbonate minerals. The world-class martite/microplaty-hematite deposits of the Hamersley Province are a special case of BIF-derived iron ore deposits that were initiated during the Proterozoic era. Evidence from overlying Wyloo Group conglomeratic horizons containing clasts of Hamersley Group BIF indicates that microplaty-hematite formed within the clasts before deposition, and that Proterozoic subaerial oxidation and weathering of uplifted Hamersley Group formations produced the microplaty-hematite in both chert-free and cherty BIF.

Jan 1, 2002

By Marwick PL

As part of its operations Hamersley Iron operates a heavy medium Concentrator to upgrade low grade, unsaleable iron ore to produce saleable lump and fines products. Firstly, the attempts at delivering a blended feed in both chemical and physical characteristics are presented. Improvements in blending controls are shown to have given process performance improvements. Secondly, improvements to the feed preparation section are detailed. These alterations are providing a much cleaner feed to the subsequent processing stages.

Jan 1, 1987

By T. Baker

The Eloise Cu-Au deposit is 60 km SE of Cloncurry in NW Queensland and has a current indicated reserve of 3.2 Mt @ 5.8 per cent Cu, 1.5gA Au and I9g/t Ag. It is hosted by metasediments and metabasic rocks that underwent amphibolite facies metamorphism at 550-600¦C and less than 3.5 kb. Peak metamorphism coincided with the regional D2 event which produced an S2 foliation with north-south strike and variable sub-vertical to steep east or west dip. The deposit is associated with several major shear zones parallel to the S2 foliation. The lodes form part of a large alteration system that is localised by the retrograde shear zones. Homblende-biotite-quartz with minor sulphides occur early in the alteration paragenesis which is overprinted by chlorite-muscovite-pyrrhotite-chalcopyrite ¦calcite+¦nagnetite. The later assemblage replaces the earlier Fe-K alteration as well as Fe-rich metamorphic assemblages such as homblende, biotite and staurolite indicating a post peak metamorphism timing for ore formation. Although replacive textures are the most common, the alteration can display open space infill and brecciation as well as durchbewegung and mylonite textures indicating that mineralisation occurred during ongoing ductile deformation. All these features are crosscut by a later brittle phase of calcite-chlorite-quartz¦pyrite alteration.

Jan 1, 1994

By Morrison R. S, Doennilan N

Recent mapping (1989-1992) by the Northern Territory Geological Survey in the Tennant Creek 1:250 000 map sheet area has resulted in substantial revision of the lithostratigraphy of the Tennant Creek Block (Donnellan, Hussey, and Morrison, in press). Briefly, the former Warramunga Group (Dunnet and Harding, 1967; Dodson and Gardener, 1978) is divided into the Warramunga Formation, and an overlying less deformed volcano-sedimentary succession, the Flynn Subgroup. The latter is conformably overlain by the Tomkinson Creek Subgroup of the Tomkinson Creek province in the north of the Tennant Creek Inlier. These two Subgroups constitute the Churchills Head Group which is essentially equivalent to the Hatches Creek Group of the Davenport province to the south of the Inlier.

Jan 1, 1994

The author reviews design evaluation theory and existing optinustion tools and then describes how these have guided recent developments in Whittle Programming's strategic mine design package: Four-X. A new package - Reserve Estimator is also d

Jan 1, 1998

Although mining, particularly of gold and coal, played a significant role in the development of New Zealand, from the time of the spectacular gold rushes of the 1860s its economic importance to the country as a whole has decreased substantially since that time. Gold, coal and non-metallic agricultural and industrial minerals have been found in economically significant quantities, however, the search for base metals has not been successful.

Jan 1, 1982

By H Mansouri, M A. Ebrahimi Farsangi, F Faramarzi

A blast fragmentation model is developed based on the gamma function to describe the run-of-mine fragmentation distribution. The model presented is aimed to benefit from simplicity in application and also to be efficient in description of the fine to coarse part of the blast rock fragments. In fact, the gamma based model (KC-KUM), gives a unit distribution curve, which is made up of two separate equations, covering different fragment sizes in the muck pile. The generated values of the fines to central part of the equation and the central to coarse part of the equation are connected at the 40 per cent grafting point. For validation, eight production blasts, which were specially designed for this purpose, were carried out at an iron ore mine (Jalal-Abad iron ore mine/Iran). Results achieved by KC-KUM and two of the most well-known models. Kuz-Ram and Swebrec, are compared with measured data. Moreover, to assess the models’ efficiency in presenting the best distribution curve, a Logarithmic error method is chosen. Based on the achievements. KC-KUM has the least deviations by the least absolute log error of 0.52, whereas the values obtained for the Swebrec and Kuz-Ram models were 0.79 and 1.34 respectively. Furthermore, the models were applied to predict X80 for 12 production blasts carried out at Gol-e-Gohar iron ore mine/Iran. These predictions were compared with the results from these trials. The coefficient of determination (R2) and root mean square error (RMSE) are calculated. Consequently, the highest R2 was obtained for KC-KUM at 0.837 with the least RMSE of 11.31. On the other hand, R2 and RMSE are equal to 0.832 and 20.19 for Swebrec; and 0.813 and 19.75 for Kuz-Ram respectively. The results obtained suggest the superiority of the KC-KUM model over the other two models in assessment and prediction of blast fragmentation in a reliable way.CITATION:Faramarzi, F, Ebrahimi Farsangi, M A and Mansouri, H, 2015. Prediction of rock fragmentation using a gamma-based blast fragmentation distribution model, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 685–692 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015