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By Coin CDA

From a study of coke samples obtained from the tuyere level of four Australian Blast Furnaces, the nature of in-furnace coke degradation has been investigated. At the periphery of the raceway is a concentration of fines and the lump coke appears dull and rounded. However coke from the deadman is angular and relatively undegraded. Cokes made from higher rank coal appear to suffer preferential attack of the reactive maceral derived component (binder). The coke from lower rank coal appears to be attacked non-preferentially by the solution-loss reaction. Initial attempts to simulate these phenomena have given results consistent with these findings. From chemical analysis of the tuyere probe samples there appears to be a relative increase in carbon and decrease in-.sulphur and phosphorous between stockline and tuyere level. An overall decrease in coke mineral matter derived material was noted and associated with this was a significant gasification of silicon. Consequent formation of silicon carbide was noted.

Jan 1, 1981

By White A. H, Vihena M. T M B

Presently, orebody modelling consists basically of fitting a mathematical model to represent spatially a certain geological variable, generally grade. An orebody model is constructed from a set of sample data obtained from various locations in the orebody, thus it is only one form of representation of the true phenomena. Checking the compatibility of the data with the modelling procedure is the most important factor when assessing confidence in the orebody model. The level of confidence in the model will depend on the adequacy of the data set and the validity of the basic assumption required by the modelling method. Fractal geometry is one way of modelling the spatial distribution of a geological variable in an orebody geometry. Fractals can be used to interpolate the Z(x) geological variable at unsampled sites. The concepts of self similarity and self affinity that form the basic assumption of fractal geometry theory which areinvestigated. The population distribution of the geological variable in question must be examined to determine the appropriateness of both fractal geometry and geostatistical modelling methods. The selection of the most appropriate method depends on the available data. A researcher or a practitioner needs to understand the strengths and limitations of the various modelling methods before choosing the most appropriate method. This study investigates the fractal properties of grade distribution using the variogram and some proposed variations as techniques to measure the fractalness. The aim is to assess applicability of fractal geometry theory to modelling ore grade distribution in a deposit. A comparison of the results demonstrates the methods which better capture the spatial behaviour of the variable under study.

Jan 1, 1995

A three-dimensional finite element analysis is used to determine the stress intensity factors associated with the chevron-notched semi-circular bend test specimen. The stress intensity factor calibration is done over a range of crack lengths a

Jan 1, 1998

By Nagai K, Moriyama K

Toyo smelter has been making s veral efforts to reduce and diversify energy for dealing successfully with such :n:;rgy problems as the first and second oil crises. ::,specially it is one of th:; most important subjects to substitute oil by alternative: energy source, because oil is expensive and unstable with respect to its supply. t _'hercfore i was decided to propel tnC ezhstitution of coal *jr oil. in the first place, the supple- mental fuel oil in the reaction shaft was replaced by oil to coal in 1981, and then th, fuel substitution of pulverized coal was achieved in the steam superheater in 1984. 3y these fuel substitutions about 7u,' of the total fuel energy at 2oyo smelter has been replaced by coal. in this paper the fuel substitu- tions at loyo smelter are described in detail.

Jan 1, 1987

By Salley J, Gould WD

The stack-gas scubber effluent from base metal smelters often contain 20-100 ppm of oxidized selenium salts. Due to their toxicity, these must be removed from solution prior to release of the effluent to the environment. Many species of microorganisms including Corynebacterium diotheriae, Neurospora crassa, Candida albicans, Escherichia coli and various species of Salmonella are capable of assimilating oxidized selenium and reducing it intracellularly to red amorphous selenium. CANMET in cooperation with several companies has developed a biological process to recover selenium from dilute solutions. The laboratory, mini-pilot plant and the large industrial pilot- plant studies leading to the development of this process will be described.

Jan 1, 1990

By Williams M

Sheet flotation is a new two dimensional column flotation cell that produces continuous spectrum of products. Analogous to a shaking table in its performance and analysis, sheet flotation is a sheet of bubbles rising through packing contained between two walls. Feed enters the sheet at the lower left and the product exit along the top and right edges. Iligh grade materials exit at the top left, middlings exit at the top right comer and low grade waste materials exit at the bottom right. As in the case of a shaking table, two motions are required: up and right. Bubbles furnish the upwards movement for hydrophobic particles, slanted packing the rightward movement for hydrophilic particles. The sheet flotation cells is analysed as a 40 x 40 array of simple cells. In practice, 1000 x 1000 arrays of simple cells may be expected. With larger arrays, excellent separations may be expected. Because there is no recycle, there is no build-up of middlings in

Jan 1, 1993

By Zamel G. I, Zenari L. P

Technological developments in modem Tunnel Boring Machines (TBMs) and associated back-up equipment are offering significant alternatives for mining operators to consider, in the selection of equipment for coal mine development drifts, roadways, longwall gate roads as well as metalliferous mining declines and development drives.Greater flexibility in handling variable ground conditions, muck disposal and radius of turn as well as advance rates, are just some of the areas where modem TBMs can accomplish the flexibility that mine operators require to achieve cost-effective developments.Compact TBMs are achieving this acceptance because of the fundamental design of a shielded machine containing electrics and hydraulics within the forward shell, ability to achieve tight radius of curvature and grades, and ability to provide highly flexible support systems to meet all possible ground conditions.However, a single TBM design will not suit all mine developments, as each development method - while having common goals with all mine developments - will also require certain unique criteria to be fulfilled.

Jan 1, 1993

By E Ruhanen, S Kauvosaari, M Kosonen, C Meintjes

The Yara Siilinjärvi plant is located in the central part of Finland. Siilinjärvi is Western Europe's only apatite mine and annually it produces 1 Mt of apatite concentrate, which creates approximately 10 Mt of tailings.At the beginning of 2017, tailings handling in Yara Siilinjärvi was brought to a new era, by replacing the conventional tailings storage facility with a new tailings treatment plant. The new high-density tailings disposal system with two paste thickeners increased the percentage of solids in the slurry from 45–48 per cent to 66-68 per cent, making it possible to deposit as a paste. This extended the life-span of the current tailings storage facility by 15 years; from 2020 to 2035.This paper presents the storyline of the Yara Paste Plant Project. The project began with laboratory testing and then progressed to pilot-scale thickening and beaching trials. After some successful pilot trials, the final process design was implemented. Process instrumentation and automation played a key role in the project, as the aim of the Yara Project was to make the plant operable remotely from the main plant. An advanced control system is needed to maintain process stability and the desired operation point in various operational circumstances.This paper discusses the results from the Yara site since the new tailings treatment plant commenced. Some of the main points are that the operation has been running consistently with an underflow solids content of 66-68 per cent, with average beach slope angles of 3.5 degrees in the tailings disposal area. This control system additionally facilitates minimum use of flocculant, which delivers significant savings to operating costs. Robust thickener operation also leads to the trouble-free high-density pumping and high availability of the Paste Plant. During the first year of operation, the plant’s availability has been very good, over 97 per cent.Currently, the plant still has its own staff working there during the daytime, but the Paste Plant is now already operated remotely during the night shifts. The long-term goal is to gradually transition into operating the plant completely remotely.CITATION:Ruhanen, E, Kosonen, M, Kauvosaari, S and Meintjes, C, 2018. Optimising the operation of paste thickening at the Yara Siilinjärvi Plant, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 297–310 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By Muir D. M

Highly saline process water has a number of implications for the CIP process during the leaching, adsorption and recovery of gold. The reduced oxygen solubility in saline water can seriously reduce the rate of gold leaching, while dissolved oxygen meters do not necessarily reveal actual oxygen concentrations in saline water. High levels of magnesium in the ground water necessitate operation at lower pH (-9), with the potential for greater cyanide loss via HCN stripping. In addition increasing salinity renders viscosity modifiers largely ineffective.The adsorption capacity of aurocyanide onto activated carbon is improved with increasing salinity, but misleading results can be obtained in assessment of gold loading kinetics of plant carbon samples already loaded, or partially loaded, in saline water if subsequently tested in fresh water. Elevated chloride levels in the Zadra elution process can cause severe anode corrosion in the elecuowinning cell. The Anglo elution process is tolerant to only slight increases in water salinity, but elution times can be reduced by ethanol addition. Care is required in carbon regeneration, as salts can catalyse carbon decomposition as well as increase kiln corrosion.

Jan 1, 1994

By Manlapig EV, Davis JJ

A methodology for modelling dense medium cyclones is presented for cyclones operating under conditions which avoid particle interference or apex crowding. Particle interference and apex crowding are shown to result in less efficient separations and represent undesirable regimes of dense medium cyclone operation. In order to avoid apex crowding, suitable medium to ore ratios and apex diameters should be used. Cyclone density differentials should be kept below approximately 400kg.m 3 to limit loss of efficiency due to excessive particle recirculation within the cyclone. The relationship between size-by-size partition curves shows that the flow split and density of the medium within a cyclone can be related to two new parameters, the pivot partition number and pivot density. The parameters are common to each partition curve in any set of size-by-size data and are mathematically related to the familiar performance characteristics, ecart probable (Ep) and separation density. The resulting expression confirms that the Ep and separation density are directly related.

Jan 1, 1986

The Western New South Wales Electric Power Proprietary Limited is the central generating authority for distribution of power to the majority of the Broken Hill mining companies and the Broken Hill Water Board. This station supplies the whole of the power to North Broken Hill Ltd and Broken Hill South Ltd. It also supplies, power to the Southern Power Corporation for distribution to the Zinc Corporation Ltd. The Southern Power Corporation has a generating station which is tied in with the central generating authority.

Jan 1, 1957

By Ault A. R

The recent modernisation program at the Risdon electrolytic zinc smelter of Pasminco Metals - EZ (PMEZ) inyolved significant changes to the composition of cell electrolytes. The most significant were increased acidity and sulphate level, a reduction in Co level, and the replacement of 2-naphthol in the additive mixture with licorice. In determining acceptable operating ranges, a relatively large number of industrial deposition tests under controlled conditions was required. The cathode zinc deposits so produced were examined in terms of overall appearance, crystal structure according to X-ray diffraction, and a micro-roughness parameter. Beginning with typical deposits produced in the presence of an excess of one of the addition agents glue or antimony or a mist suppressant (licorice or 2-naphthol), a simple classification system was developed. In this system, the deposits are divided into the following types: Doughy, Pinholed, Compact and Stressed. There was a weak correlation between deposit type and crystal orientation. In terms of ease of stripping, observations in plant operations showed that only Compact and Pinholed were consistently acceptable. Current efficiency was normally maximised by producing a Compact deposit. Process variables such as zinc concentration, temperature and the use of strontium carbonate were found to cause changes in deposit type if the reagent mixture used was unchanged. From the knowledge gained, guidelines were developed to allow glue and antimony additions to be altered to fit new circumstances. The simple classification system was first used to expedite recovery from undesirable morphologies and then to optimise individual cell units operated under substantially different conditions. It is believed that finer control could be exercised by determining the micro-roughness of Compact deposits. However, difficulties can arise if sudden, large deviations occur and go undetected. Suggestions are given for an improved additive control system. The classification system developed has been compared with published information in the literature, and good correspondence was noted suggesting a predictable relationship between short-term, laboratory deposition tests and observable phenomena in industrial electrowinning cells run under steady conditions.

Jan 1, 1993

Prior to 1975, most geochemical drainage surveys for gold were based on analyses for pathfinder elements, such as As and Cu, rather than direct analysis for gold, for two reasons. Firstly, analytical methods lacked the required sensitivity and precision to determine gold abundance at background levels in stream sediments (usually in the range 1 - 10 ppb). Direct analysis was also inhibited by concern about the potential for gross sampling error, brought about by the dispersion of gold as rare discrete particles of the extremely dense native metal. This sampling error, commonly termed the 'nugget effect' has two components: erratic distribution of the element within the stream environment, related to hydraulic factors, and the difficulty in taking representative samples, both in the field and later in sub-sampling for analysis. In more recent years the collection of very large samples was commonly advocated to overcome the sampling problem (Hams, 1982; Nichol, 1986).Two methods have been widely used to evaluate the gold content of bulk samples (Elliott and Towsey, 1989). The preparation and analysis of heavy mineral concentrates has in recent years been largely superseded by the leaching of gold contained in bulk samples by cyanide, commonly termed the BLEG (Bulk Leach Extractable Gold) or BCL (Bulk Cyanide Leach) methods. The terms BLEG and BCL are essentially interchangeable and the latter will be adopted for the remainder of this paper. The strengths and weaknesses of these two techniques were compared with conventional total gold analysis on fine fraction (

Jan 1, 1976

By W A. Peppin, D N. Riley, N W. Schulenburg

In June 2008, a joint airborne collection using hyperpspectral systems was tested on a single Twin Otter aircraft. This experiment was designed to incorporate two airborne hyperspectral sensors for geological and environmental projects. Mineral exploration and environmental impact statements are two areas where full spectrum hyperspectral data can document the mineralogy at the surface prior to mining operations. Many previous hyperspectral remote sensing collections were collected on a single aircraft with a single sensor. Mineral mapping using hyperspectral sensors that measure in complimentary regions of the electromagnetic spectrum is cost effective as it allows for the mapping of clays, sulfates, carbonates, feldspars, quartz, garnets and many other minerals. This report describes the experiment using the following two hyperspectral sensors: ProspecTIR, a visible near and shortwave infrared (VNIR-SWIR) sensor with 356 channels and spectral range of 0.4 to 2.5 ¦m, along with a spatially enhanced broadband array spectrograph system (SEBASS), a midwave and longwave infrared (MWIR-LWIR) sensor with 128 channels from 2.5 to 5.3 ¦m and 128 channels from 7.6 to 13.5 ¦m. SpecTIRÆs ProspecTIR system and The Aerospace CorporationÆs Spatially Enhanced Broadband Array Spectrograph System (SEBASS) are pushbroom sensors, have high signal to noise ratios, have similar swath widths and instantaneous fields of view. Examples of data collection experiment will be shown with a focus on mineral/lithologic identification and mapping along with environmental assessment in the western United States. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

This paper describes the effects of physical variables in dewatering of mineral slurries with air as the filtrate displacing medium. Using a mathematical model with material related constants measured in laboratory dewatering curves are simulated for vacuum and pressure filtration. Four different mineral slurries are studied. Basic dewatering curves with variation in air-pressure are shown with iso-energy lines. Variables such as air pressure, feed concentration, cake thickness and cake formation pressure are discussed.

Jan 1, 1989

By M Bannear, J-F Wilhelmy, R Jones

Mineralogical study of the interactions between fluxes and iron-oxides helps to understand how magnetite oxidises to haematite during pellet firing. Samples of OneSteel magnetite pellets tested at COREM pilot plant were collected after three firing steps and were studied mineralogically. Preheated pellets revealed no particular microstructures related to the composition of fluxes but were more affected by their bed position. After kiln firing, the impacts of lime and magnesia became more apparent. Magnetite oxidation is complete in the cooling stage. The position and the microstructure of the residual magnetite can bring useful information that could æcompleteÆ the view of the firing cycle.

Jan 1, 2007

The Golden Valley Volcanic Centre has been recently interpreted as being a combination diatreme breccia pipe and rhyo-dacite flow dome complex of Permo-Carboniferous age that intrudes basement granitoids and sediments of Ordovician-Devonian age. Exceptionally good exposure at the Centre has enabled the relationships between different lithologies to be determined. This, along with petrological studies, has led to a detailed understanding of the geological environment in which the complex formed. Gold, silver and base metal mineralisation have been recently shown to be associated with the Marginal Breccia at the perimeter of the diatreme. Comparisons have been made between the geology and mineralisation in this system and several similar diatremes which also contain gold-base metal sulphide mineralisation.

Jan 1, 1990

Geostatistical conditional simulation is a method to assess variability and risk in mineral deposits and the tool has wide potential applications in the iron ore industry. Correct reproduction of multivariate relationships is important in iron ore simulation, especially between Fe and impurities such as Al2O3, SiO2 and P. The turning bands simulation method, using a full model of coregionalisation for multiple attributes, is the main multivariate conditional simulation algorithm used in the Western Australian iron ore industry. This paper discusses the results of a more recent approach using minimum/maximum autocorrelation factors (MAF) to transform and decorrelate the multivariate data prior to independent sequential Gaussian simulation (SGS). MAF-SGS results are compared to those of the turning bands approach in the Yandicoogina channel iron ore deposit (CID), and both methods performed well in simulating Fe, SiO2, Al2O3 and P distributions. Extensive checking of simulations showed that both approaches could reproduce multivariate statistics and spatial continuity of the original conditioning data. Both approaches reproduced the histograms and variography of input sample composites. While the MAF-SGS approach requires additional transformations when compared with the single normal scores transformation required for the turning bands method, MAF requires only that the direct semivariograms be modelled. In contrast, using turning bands with multiple attributes requires modelling a full linear model of coregionalisation, which can be difficult to model because of the need to ensure the model is positive semi-definite. Turning bands may be preferred if there are a modest number of correlated variables allowing construction of a linear model of coregionalisation that adequately models the multivariate behaviour. MAF-SGS is preferable for larger numbers of correlated variables. Both MAF-SGS and turning bands methods performed well in conditional simulation of correlated variables at Yandicoogina.

Jan 1, 2007

Future hard rock mining will gradually move towards complete mechanisation which lends itself to remote control and ultimately to robotic mining. This will require different technical inputs into mining engineering and one of these is in the area of rock'mechanics. Traditional hard rock mining has had little rock mechanics input. Problems arising from high stresses and poor ground conditions have in most cases be remedied after they occurred, in the worst case by abandoning a particular stope or area and starting elsewhere. In a fully mechanised remote or robotic mining situation the financial penalty for such an approach could be severe, as a major part of the production costs will be in the development and the equipment. It is therefore imperative that a complete rock mechanics feasibility study is undertaken before an area is set up for robot mining and that a continuous stability monitoring system is installed that will predict rock behaviour well in advance of mining, such that the necessary ground control measures can be implemented without impeding the continuity of mining. This system will utilise already existing instrumentation such as extensometers and stress cells, and possibly additional improved instrumentation which has to be developed for this particular Application.

Jan 1, 1986

By Fabjanczyk M. W

The design of underground mine roadways (tunnels) requires a detailed understanding of the in situ stressfield, the rock failure modes, the performance characteristics of reinforcement or support members and assessment of the stress state about the roadway. Definition of these factors, together with monitoring of roadway behaviour during both development and extraction operations, allows rational design procedures to be undertaken.The design approach utilised computational techniques to simulate the behaviour of the strata about the opening for a range of anticipated stressfields and various reinforcement options. Field validation studies are conducted to confirm the design expectations.

Jan 1, 1993