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By Y Yang

Despite the importance and usefulness of basicity in metallurgical slags, the optimum quantitative expression of it has remained elusive, partly due to the fact that the precise concept of basicity has not been properly clarified. The two basic approaches to the concept of basicity are the Lux-Flood, which perceives basicity in terms of the activity of the free oxide ion, aO2-, and the Lewis, which perceives basicity in terms of the ability to donate negative charge. The former has been almost universally adopted in the area of metallurgical slags, while the latter has been increasingly accepted in the field of glass chemistry. In this paper, some difficulties of the Lux-Flood approach are pointed out, including the need for indirect measures of aO2-, which have proliferated in recent years. Accordingly, it is suggested that the Lewis approach has a good deal to commend it, and that the quantification of it in terms of optical basicity is the best measure of basicity available, which should therefore be more widely applied in metallurgical slags than it currently is. The fact that there are intrinsic problems in evaluating the optical basicities for the transition metal oxides is acknowledged, and a new scale is recommended. The patterns of iso-optical basicity lines in ternary systems are shown to agree well with the pattern of iso-activity and iso-capacity lines under appropriate conditions.

Jan 1, 2000

By Wright S

Single pellets of mixed lead-zinc concentrate containing up to 20 % lead were roasted in the temperature range of 800-1100¦C. Variables studied included pellet size (from 9-8 to 3-2 mm diameter), gas flowrate past the pellet (from 0.05 to 5 ms t), composition of the atmosphere and the effect of additives such as zinc oxide and silica. After defined periods of time, the pellets were removed from the furnace, quenched and submitted for chemical, XRD, SEM and microprobe analysis. The oxidation of the zinc sulphide followed a shrinking core model. Temperature measurements showed that very high pellet temperatures were experienced at the start of an experiment but after 5-10 minutes these approached a constant temperature. The lead loss from the pellets was then constant with time. Thermodynamics predicted the presence of two bands of lead material in the reacted layer of the pellet. These were found in practice. The lead loss from the pellet occurred from the outer oxysulphate layer via the vaporization of lead oxide polymers. The vapour pressure of PbO, and the loss of lead, was dependent on temperature and bulk gas concentrations of SO2 and 02. At 1100¦C the addition of silica greatly reduced the loss of lead from the pellet. Physical factors such as pellet diameter and gas flowrate past the pellet affected the particle dynamics. These results were found to vary in accordance with the predictions of the Froessling equation.

Jan 1, 1989

This paper comprises a discussion of standards for comparing conditions in mines, of methods for measuring the flow of air, of a comparison of fan performances, and the application of these matters to mines in Western Australia.UNDERGROUND CONDITIONSIn approaching the question of mine ventilation one naturally searches for some standard by which to measure the conditions in a mine.There are several clauses in the Mines Regulation Act defining the conditions which are permitted. The quantity of CO2 is limited to 0·25 by volume, but the estimation of CO2 involves a chemical determination and is not suited for general use in a mine.The maximum temperature is fixed at 87 0 F. (dry bulb), and at 80° (wet bulb). The reading of temperature is easily done in the working places, and this is a very valuable and practical test of the conditions in a mine.The wet bulb temperature is probably the most important factor in determining working conditions. It is obvious that human life cannot be sustained for any appreciable period if the wet bulb temperature is above blood heat (about 97°F.). In places where the wet bulb temperature is 90°F. there is danger of heat stroke.In places where the air in a mine is still, the wet bulb temperature rises to a value close to the rock temperature.Adequate ventilation cools the workings by transference of heat from the rock to the air stream, and the temperature...

Jan 1, 1939

By Hegedus M

The Hydrogeological Survay of the bauxite mines in Hungary was establisned 30 years ago. The goal of the HS has been to collect the all available date needed to solve the hydrogeological problems of bauxite mines. The results of activity of the HS have been summarized in the annual reports-. This report is going to present a few methods to evaluate the hydrogeological properties of fissured, karstic rock ie. the evaluation of drilling mud losses, the statistics of core samples evaluated by a special computer program for calculation the porosity and permeability of the rocks. An experimental injection test is presented together with the development of a new portable instrument to get signes of the water table change during the injection test in every two second. It can be proved that the flow around the well may be a transient one if the yield of the injection exceeds a definite one (Figure 2.). It was observed that the permeability calculated from the pumping test date may be 1.2-1.6 time higher than it coming from the injection test. A practical example is presented also how to use the results of the HS for designing the dewatering of a new mine together with an analogous computer model to forecast the yield expectable for making the drift tunnel. A suggestion based on the hydrogeological feature has been done for the dewatering without using electric energy (see Figure 3.-6.).

Jan 1, 1988

Naturally occurring organic plastics have been in use for over 2,000 years. Plastics based on chemically modified organic polymers date back only about 100 years, and those based on synthetic polymers about 50 years. The development of ,these two latter groups up to the present day is outlined, and the basic techniques currently available for polymer-building and modi-fication (blending, copolymerisation, quantitative and qualitative struc-tural control, and'si de-group reactions)-are reviewed.

Jan 1, 1962

By K L. Silversides

Shales form distinctive peaks in natural gamma downhole logs, which are used to manually identify the location of ore boundaries. These shales form important lithology markers that can potentially be automatically identified using Gaussian processes. This approach is trialled using data from a typical iron ore mine in Western Australia which contains the Marra Mamba sequence of the Hamersley province.The method uses Gaussian processes (GPs) with a single length scale squared exponential covariance function. A library of 8 m sections, where natural gamma measurements were taken at 10 cm intervals down the hole, was used to train the GP model. This library was iteratively improved and was tested using natural gamma logs that were not included in the library. Areas that were misclassified or were not clearly classifi ed were added to the library. The new library was then used to train the model and improve the results. The trials used a double gamma peak from the NS3 and NS4 shales at the boundary between the Newman 1 and Newman 2 ore zonesin the Newman member and the AS1 and AS2 shales at the base of the West Angelas member. The results show that both boundaries can be identifi ed with an accuracy of over 99 per cent. The classification has the highest accuracy on undeformed shales. This method provides a fast, accurate and objective identifi cation of shale and ore boundaries and can potentially replace the current manual detection.

Jul 11, 2011

Dr. F. L. Stillwell. Segnit's article puts forward the views that the rocks associated with the Broken Hill lode are simply highly metamorphosed sediments, tbat metasomatism on a large scale was not an important factor at Broken Hill and that the rocks and lode were contemporaneously metamorphosed.In particular, the garnet quartzite, the most abundant rock in the limited section of the mine examined by Segnit, is described by him as a simple, metamorphosed manganiferous sediment.These views, while consonant with those of H. F. King (1958), are drastically opposed to those of myself and others e.g. Gustafson et al. (1950, p. 1383) who state that the most extensive hydrothermal alteration in the district is in and close to the zinc lodes in the Zinc Corporation and New Broken Hill Consolidated Ltd. mines. Segnit's conclusions conflict with 1. the absence of any manganiferous sediment in the Broken Hill district except in close proximity to the lode,2. the clear cut metasomatism of the dolerite dykes which indicates that the ore is younger than the dykes and therefore post-metamorphism, and 3. the petrofabric study of den Tex (1958) which provided independent evidence that the ore in its present form post-dates all events of a diastrophic nature in the area.The original sediments of the district were mudstones and calcareous sandstones with 2 to 5 per cent CaO. These have been converted by high grade metamorphism into sillimanite gneisses and quartzites characterized by the presence ...

Jan 1, 1962

By Will D. P

A 328 m, 2.4 m diameter raise-bored shaft has been equipped with a modular ladderway system to provide a second means of egress from Aberfoyle's Hellyer Mine in Tasmania. The modular ladderway consists of platforms, ladders and service pipes assembled at the surface and progressively lowered down the shaft. This system provides a rapid, safe and economical non-entry approach to equipping a shaft. The modular construction and single suspension allows for future extension or for reuse in another shaft.

Jan 1, 1988

By Woodcock JT

This paper deals with some innovations and current proposals for the treatment of gold ores and considers the possibilities of incorporating new developments in new or revised ore treatment flowsheets. The main topics considered are I. typical practice in relation to the size of gold particles, 2. concentration of coarse gold, 3. leaching reagents, 4. in situ leaching, 5. heap leaching, 6. carbon-in-pulp adsorption, and 7. treatment of complex ores (gold in pyrite, gold tellurides, and carbon-containing ores).

Jan 1, 1982

By Kinsella B

Titrimetric studies have been carried out on the activated carbons Kintal 1105, Norit 2520 and Kuraray 2GA. Titration curves of the carbons before and after acid and water washing and gold loading indicate that the acid-base properties of the carbons are affected by both the method of treatment and also by the loading of gold. It is considered that the pKa values of the functional groups on the carbon surface are in the regions of 11, 7 and 3 respectively.

Jan 1, 1984

One of the often overlooked factors affecting the capital investment decision in new or existing plants is the value of stock holdings necessary to maintain the plant. This paper puts forward a simple decision matrix on whether a part should be stocked depending on 1. the criticality of the item of equipment in terms of the effect on cash flow of its failure, 2. the lead time of the part, and 3. the stock holding value if it were Stocked.

Jan 1, 1986

Through partnering with mining customers, DYNO has been able to develop some specific technologies that benefit blasting operations particularly in underground mining. Some of these areas are: 1. Cost allocation and product tracking systems; 2. Borehole video surveys of breakthrough blastholes; 3. Borehole video photography for logging VRM blastholes; 4. Toe-load uphole loading for sublevel cave mining operations; 5. 3D blast modelling for underground ring blasting. This paper outlines these developments in the context of a Canadian underground metalliferous mine.

Jan 1, 1995

By Willett, Jacka

Group 3 were asked to discuss the treatment of spontaneous combustion. Before discussing specific cases we agreed that certain preliminary information should be available. The following questions are typical of the information which might be requested: 1. Have workmen been withdrawn? 2. Have gas samples been taken? 3. Is the mine gassy? 4. What are the details of water supply? 5. Are mine plans available? 6. What equipment is available? We discussed treatment in four different circumstances as follows: 1.

Jan 1, 1973

By M Suzuki

Although several models for the surface tension of molten oxide slag have been proposed, suitably accurate predictions of this property are not yet possible. The surface tension, or surface excess free energy, of molten oxides is largely determined by the ionic coordination induced by surface relaxation. However, the associated mechanism of surface structural relaxation for molten oxide mixtures such as slag is complex and not yet fully understood. To allow a better evaluation of surface relaxation characteristics, the present work analysed the ionic coordination associated with the surface-relaxed states of several oxide mixtures. This work especially focused on calcium aluminate slags because these materials exhibit complex relationships between composition and surface tension. The effects of incorporating low concentrations of SiO2 as a surface active component on the surface ionic coordination were also examined. X-ray absorption techniques were used to assess oxygen and cationic elements in glassy samples after surface relaxation treatments, and molecular dynamics simulations based on a polarisable ion model of molten slag with vacuum/melt interfaces were also performed. The X-ray absorption techniques provided data related to electron yields (which are primarily associated with surface features) and fluorescence yields (which evaluate the bulk material). Thus, the ionic coordination characteristics of both regions were investigated. The results of molecular dynamics calculations allowed statistical analysis of the distributions of Al- or Sicentred polymorphs as well as the bond angles between cations and oxygen anions in the vacuumexposed and bulk regions in the equilibrated melt. The results indicated that bridging oxygen ions were preferentially distributed in the relaxed surface region rather than non-bridging oxygens. These bridging oxygen ions represented vertex connections between AlO4 or SiO4 tetrahedra. In the case of the calcium aluminate slags, the addition of one Ca2+ ion as charge compensation for two Al3+ ions was found to be necessary to form two AlO4 tetrahedra. This specific feature of surface ionic coordination could be responsible for the complex trends observed in surface tension data. The incorporation of low concentrations of SiO2 reduced the proportion of tetrahedrally-coordinated Al ions such that higher coordination states become dominant in the bulk of the material, whereas AlO4 tetrahedra were preferentially distributed in the surface region. SiO4 tetrahedra were the preferred Si-centred polymorph and were likely connected to one another to form bridging oxygen ions at the surface. On the basis of these results, a model to predict slag surface tension was proposed, and the energy of the formation of the ionic clusters resulting from surface relaxation was taken into account.

Aug 21, 2024

Sample preparation for gold samples, where the distribution and size of gold particles is often irregular, usually demands that a relatively large sample weight is taken to produce a representative sample for analysis. Traditional sample preparation of gold samples incorporated multiple stages of coarse particle size reduction followed by subdivision of the sample prior to final fine pulverising. This technique developed because of the limited equipment options available to laboratories. As a result significant errors are introduced and the final sample size being pulverised is a small fraction of the original sample weight. Three significant developments have occurred in the last 25 years to significantly improve sample preparation of gold samples: 1.  large capacity fine pulverising,2.  fine jaw crushing, and3.  whole sample coarse pulverising. In the mid-1980s an Australian manufacturer developed large capacity pulverising bowls which had the ability to reduce samples with a mass of 1.5 - 3.5 kg to a nominal 0.075 mm product in approximately three to five minutes. Laboratories were able to produce a large homogeneous pulverised sample which significantly reduced the error in sampling. However, exploration and mine samples are usually 7 to 10 kg and the sample requires a subdivision stage following crushing to produce the 3.5 kg for the pulverising step, thus introducing potential for significant error. The development of fine jaw crushing allowed particle size reduction to -2 mm which reduced the subdivision error of the bulk sample prior to fine pulverising. Subdivision of the crushed sample at -2 mm still results in potential sampling errors, where the gold particles are not sufficiently liberated to be representatively sampled. Clearly the best option would be to reduce the particle size small enough to ensure a representative sample prior to final pulverising. Continuous mills offer a partial solution but are relatively slow and subject the sample to differential pulverising prior to subdivision. Clearly this does not provide the best solution for routine laboratory applications where high volumes of samples are to be processed. The recent development of a large capacity coarse pulverising system allows samples of up to 10 kg to be reduced to -0.25 mm prior to subdivision, and fine pulverised to -0.075 mm. Laboratories now have the necessary equipment to perform reliable large capacity sample preparation of gold samples. The exact choice of a sample preparation scheme may still depend on particular ore types but the need for multiple crushing and subdivision stages is redundant.

Jan 1, 2008

By W J. Bruckard, M J. Vaisey

Ashton Mining Ltd (Ashton) and Lynas Corporation Ltd (Lynas) have established a joint venture partnership to develop and process rare earth oxides (REOÆs) from the Mt Weld deposit in Western Australia. The deposit is located in a deeply weathered volcanic carbonatite structure that contains approximately two million tonnes of rare earth oxides at an average grade of 20 per cent REO. As part of the 1999/2000 feasibility study currently being undertaken by Ashton and Lynas, an extensive laboratory beneficiation test program was undertaken by CSIRO Minerals on diamond drill core samples from the Mt Weld orebody. The aim was to develop a flowsheet, based primarily on flotation that could be confirmed at pilot plant scale. The target concentrate grade was 52 per cent REO with a REO recovery of at least 35 per cent. Two main ore types, nominated as CZ (limonitic siltstone) and LI (nodular limonitic ironstone) were identified for separate laboratory evaluation. The lower grade LI-type ore overlies the higher grade and more extensive CZ-type ore. The majority of the work was conducted on the CZ ore; only limited testing of the LI ore was undertaken. The latter contains a clay component that will present difficulties in processing due to its poor filtering and settling characteristics. Two processing options for treatment of CZ ore were presented for pilot plant consideration. One (Option 1) includes gravity concentration prior to flotation while the other (Option 2) includes finer grinding and four stages of open circuit cleaning. The benefits of each scheme are discussed in detail. Neither has been fully optimised and the definitive flowsheet is most likely to be a hybrid of the two schemes, incorporating the best features of each. Typical metallurgical results from each scheme were final concentrate grades of 49 per cent REO, 10-16 per cent Fe2O3 and 3.2-4.8 per cent CaO. REO recoveries were above 35 per cent in both cases. Features of the processes developed by CSIRO were the inclusion of a gravity concentration stage prior to flotation, a modified flotation reagent scheme, a change in the method of feed preparation, and incorporation of magnetic separation to upgrade final flotation concentrates. Metallurgical results obtained from flotation tests on LI ore were much poorer than those obtained for CZ ore. The best rougher/scavenger result, with the limited amount of testing so far completed, was an REO grade of 32 per cent with a recovery of 28 per cent. Further work is needed to develop a viable processing route for this ore type.

Jan 1, 2000

By R H. Boffey

The Osborne copper-gold deposit was discovered in North-West Queensland in 1989. Underground production activities commenced at Osborne deposit in April 1996. This paper will examine technical and operational aspects of the underground mine during its development to a 1.2 Mtpa operation . Technical aspects discussed include geology, mine design and mining methods, equipment fleet selection and capital infrastructure. Operational aspects discussed include the evolution and performance of the integrated work teams that are utilised at Osborne to perform all mining and maintenance activities.

Jan 1, 1998

As modern techniques of Petroleum Exploration and Development are rela-tively new in Australia,2 the alien terms "Mud Logging" and "Core Analysis" will bear explanation. Mud Logging and Core Analysis are two of the Petroleum. Industryts most useful "tools" in the successful search for, and development of, commercial oil and gas deposits. Modern Mud Logging could be more accu-xately termed "Drill Cuttings and Mud Gas Analysis". Presently, mud-logging has its greatest application in exploratory wells where subsurface geologic control is at a-minimum.

Jan 1, 1962

By R Uken G P Whitmore

The coastal dune cordon of northern KwaZulu-Natal is amongst the highest in the world reaching heights in excess of 180 m and up to 2 km in width. It comprises a complex system of Quaternary stacked dunes of various geomorphologies, types and ages. The dunes contain economic heavy minerals which are currently exploited ~20 km north of Richards Bay. Although mining of these ore sands has been in operation for the last two decades, little work has been undertken on the clay-fraction (

Jan 1, 2001

By T J. Sheer

The removal of airborne pollutants from underground ventilating air is discussed. The work concentrates on the removal of CO, CO2, NOx, SO2, radon gas and respirable carbon particles. The investigation combines techniques for multiple contaminant removal using forced chemical absorption and oxidation. Both dry and wet scrubbing techniques are employed. Mixed success has been achieved in the tests carried out and this paper is seen as a progress report on the work done to date. The interference and interaction of the gases on the individual removal efficiencies is a very important factor in the finalisation of a macro air conditioner (MAC) design for treating underground ventilating air. This necessitates a specific sequence of contaminant removal. Efficiencies are discussed and recommendations made. Wet forced chemical absorption and oxidation processes, though efficient in terms of removal efficiencies, cannot be employed in the confined underground environment due to safety and health risks. Impacts on the internal water reticulation systems of the mine have been analysed to determine the effect of future large-scale macro air conditioning practices, including blow-off liquids discharged into the water circuits. To engineer the safety and health risks out of such designs can be costly and it is for these reasons the research now concentrates on dry scrubbing of the contaminants from the underground ventilating air. The paper concludes with statements on the benefits of macro air conditioning in deep hot mines, in both recirculating and series air ventilation distribution strategies. These benefits include reduced re-entry times after blasting and increased production rate opportunities.

Jan 1, 2005