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By Lorenzen L

In South Africa, as in many other countries, the young engineering graduate is promoted quite soon to a management position where he uses less technical skills and more people-oriented skills. In the standard undergraduate curriculum for engineering, little attention is paid to the non-technical issues of the profession. An undergraduate course in management techniques cannot be a substitute for a MBA or Masters degree in engineering management, but can at least create an awareness of the practical problems facing the engineering manager. The aim of this paper is to provide an outline of such a course structure at the University of Stellenbosch. A survey is also presented on management training in the South African and Australian mineral industries. Feedback from students and graduates indicates that the fresh graduate does not fully appreciate the value of such a course until he/she achieves a position of responsibility after two or three years. Nevertheless, the management course appears to be successful in widening the perspectives of the engineer. As explained frequently in management journals, the technically oriented person (the engineer) has a convergent thought pattern, which could be in conflict with the more divergent thought pattern of the top, personnel or marketing manager. It becomes increasingly imperative for the young minerals engineer to be externally oriented instead of the traditional internal focus of engineering. The engineer should not only be aware of environmental issues in the technical design and operation of plants, but should also understand the inter-relationship between public relations, political pressures and environmental perceptions vis-d-vis technical facts.

Jan 1, 1993

By Pilkington T, Noy A

The Yallourn North Extension (YNX) open cut mine ceased mining operations in early 1989. YNX may be used again for coal supply at the discretion of the Coal Corporation Of Victoria (CCV); this has resulted in the need for interim rehabilitation of the site which may last many years, or indeed, permanently.The site has suffered substantial surface erosion over the years with large areas of bare clay and coal batters remaining exposed. The first priority is to reduce the quantity and improve the quality of stormwater runoff from the site. This is best achieved by appropriate revegetation and the use of existing landform depressions as silt trap/wetland areas. Proposed rehabilitation needed to take into account the sensitive fire safety of the open cut and the option to re-open the mine if CCV deems appropriate.The authors detail the factors involved in the rehabilitation proposal and the multi-disciplinary approach to planning including engineers, scientists, a forester, landscape architects and community input. The rehabilitation design included early consideration of land use and ongoing maintenance issues linked to water quality improvement factors including vegetation. Engineering input was required for reshaping and clay covering exposed coal batters and the design of silt traps which will revert to wetlands in future. The integration of each discipline has produced a rehabilitation design pleasing to both the SECV and community alike.

Jan 1, 1992

By K Heiskanen, R A. Grau

Gas velocity (Jg) measurements conducted close to the froth-pulp interface over the cross-section of a flotation cell reveal how efficiently the incoming air is being dispersed throughout the volume of the cell. Furthermore, measurements of Jg at deepest locations in the cell provide valuable information about air recirculation and dispersion conditions in the bulk volume of the cell. Gas velocity in flotation cells has predominantly been measured by a transient capture of gas in a graduated probe. In this project, a new sensor for measuring gas velocity in an on-line manner was developed. A probe is partially immersed in the flotation machine, below the froth-liquid interface. The probe is used to collect the rising air bubbles from the liquid phase. The liquid-froth interface is shifted into the probe under vacuum. A controlled vacuum is kept inside the probe. As air bubbles burst inside the probe, the excess of air is continuously removed from the probe via suction. The removed air is measured using a mass flow meter. The fully automated sensor allows us to continuously measure Jg at different location in a flotation machine. An experimental programme was carried out in a 10 cm diameter laboratory flotation column to determine the accuracy and repeatability of the automated sensor. The new sensor was used for evaluating gas dispersion conditions in a 215 litre transparent laboratory scale flotation cell. Gas velocity distributions along the radial and axial directions of the cell were measured over a wide range of operating conditions. The operating conditions in the cell were modified by altering impeller speed and air flow rate. Two different rotor-stator mechanisms were utilised to disperse the air in the cell, the MultiMix and the FreeFlow mechanism. In this paper, a description of the gas velocity sensor is given, and the results of the experimental work are discussed in detail.

Jan 1, 2005

By H S. Shin, H Jin, B H. Ryu, J Lee

Prospecting ice on the Moon necessitates drilling systems to obtain subsurface samples and measure the composition of ice deposits. Landers and rovers equipped with drilling equipment are essential for analysing ice and subsurface resources located at the Moon’s poles. These devices must be small, lightweight, low-power, highly efficient, and high-performance units to function properly in the extreme conditions of the lunar environment. Researchers have developed a prototype drilling apparatus capable of operating in atmospheric and cold environments. A newly developed drilling system in Korea, capable of performing not only sampling but also subsurface investigation, is introduced.

Sep 1, 2024

By Worotnicki G, Tillmann V. H

Past experience with fully bonded cable dowels placed as a means of reinforcement in highly stressed crop pillars at the New Broken Hill Consolidated Limited (NBHC) mine indicated such support was not fully effective. Typically overbreak of the crown occurred leaving long lengths of cables hanging from the back stripped of grout and rock with the potential load carrying capacity of the cables not having been fully utilised. This mode of behaviour had been observed in the cable dowelled crowns of three longhole open stopes (EROS) mined to the No. 12 level at NBHC. A system of support with improved mechanism of load transfer from rock to cable and capable of full utilisation of cable strength was proposed for the crown pillars of future Stopes.

Jan 1, 1983

By Bogar D. V

Often dewatering of coal tailings is inhibited by the presence of clays, making it difficult to obtain a high concentration, handleable coal tailings. The net result can be a low concentration, chocolate mousse-like tailings which poses significant sedimentation problems in a tailings dam and represents a significant environmental problem. This paper examines the coal tailings from a Hunter Valley colliery where the tailings properties are influenced significantly by the presence of montmorillonite clay. The influence of the calcium ion on the rheology and sedimentation/compression behaviour of coal tailings . containing montmorillonite already dispersed in water was investigated and revealed that very little improvement in the properties is achieved through the coagulation. The preliminary investigations also indicated that the properties of the tailings were dominated by the presence of the montmorillonite clay. Thus investigations were carried out on the clay alone in water. Investigations into the effect of dispersing samples of the clay alone in water and then coagulating with calcium compared with dispersing the clay directly into calcium ion solutions at the same calcium concentration showed huge improvements in the rheology, compressibility, sedimentation rates and sediment solids concentrations for the second dispersion method, which can be called controlled dispersion. The sediment volume fraction solids improved by more than a factor of two by controlling the dispersion of the clay. The reason for the improved properties lies in the suppression of the initial swelling of the clay, which is initially in the sodium form, thus maintaining the parallel orientation of the platelets that is present before wetting. While swelling is being suppressed, ion exchange occurs with the calcium which results in permanent swelling suppression. In the uncontrolled dispersion case where swelling is uninhibited, the clay is allowed to break up and despite the powerful coagulating nature of the calcium ion, the random orientation of the high aspect ratio clay platelets inhibits effective coagulation. Results indicate that the initial electrolyte concentration of the washwater in a coal washery is the critical factor controlling the dewaterability of clay tailings and the handleability of the dewatered product rather than the actual act of coagulating with the calcium ion. The results presented are of clear practical significance and indicate how coal tailings problems where clay dominates the rheology can be improved considerably by knowledge of the surface chemistry.

Jan 1, 1995

By M I. Pownceby, N A. S Webster, J Manuel, N Ware

The properties of iron ore sinter – commonly defined by measures of tumble strength, reduction degradation and reducibility – have a major impact on blast furnace performance. These properties are largely influenced by raw material properties, in particular the bulk ore composition. Despite this importance, there is a lack of quantitative data on the impact of ore chemical composition on iron ore sintering. This is surprising since the levels of Fe, SiO2, Al2O3, P, MgO and other elements, together with the nature of the minerals in the fine ore, play a major role in determining the abundance and type of high-temperature bonding phases that form during sintering. It is the abundance and nature of the high-temperature bonding phase(s) that directly influences sinter quality. This study combines in situ diffraction experiments in model sinter systems with laboratory-based compact sinter tests using natural ores to examine the links between iron ore composition and sintering temperature and their effects on standard metallurgical sinter quality test methods. Results help to establish the critical compositional and thermal parameters that control the bonding phase chemistry, which in turn influences the physical characteristics of the sinter matrix. This information should enable operators to predict optimum sinter operating conditions based on the initial chemistry and mineralogy of the iron ore fines and recognise the chemical modifications to the original iron ore fines required to produce high-quality iron ore sinter.CITATION:Pownceby, M I, Webster, N A S, Manuel, J and Ware, N, 2015. Iron ore geometallurgy – examining the influence of ore composition on sinter phase mineralogy and sinter strength, in Proceedings Iron Ore 2015, pp 579–586 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By R-H Yoon

Increasing the upper particle size limit of flotation would allow operators to increase mill throughput, save operating costs, simplify flow sheets, and increase rate of return. However, coarse particle flotation is difficult for various reasons, of which bubble-particle detachment has been identified as the major limiting factor. In the present work, the process of bubble-particle detachment has been studied by directly measuring the forces required to detach air bubbles from hydrophobic solids. The measurements were conducted using a hanging balance apparatus. The measured forces were converted to detachment energies that can be compared with the work of adhesion, which in turn is a function of hydrophobicity, surface tension and contact area. The results were converted to detachment energies using the Young-Laplace equation for capillarity. In the present work, the solid surfaces were hydrophobised by coating them with octadecyltrichlorosilane and cetyltrimethylammonium bromide. The results show that bubble-particle detachment occurs in two steps. In the first step, air bubbles are deformed, while the three-phase contact (TPC) line is pinned, until contact angle reaches advancing angle. In the second step, the TPC line moves along the surface until solid/air interface is replaced by solid-liquid interface. In general, the energies of detachment measured in the second step are in good agreement with calculated work of adhesion. Thus, the energy required during the first step effectively represents an energy barrier for bubble-particle detachment. It has been found that the energy barrier varies with surface roughness and surface tension. The results of the present investigation suggest, therefore, that coarse particle flotation can be improved by control of particle hydrophobicity, surface roughness, and surface tension.

Jan 1, 2005

The Crown Minerals Act 1991 has introduced some significant changes to the New Zealand mining industry, not the least of which relate to the ability of miners to obtain access to land to conduct mining activities. This paper briefly reviews the relevant provisions of the Crown Minerals Act dealing with access arrangements, considers some typical features of access arrangements and examines a number of areas where problems may arise.

Jan 1, 1992

The products from beneficiation present themselves at opposite ends of the spectrum, and yet numerous synergies exist in the preparation of coking coal and hematite iron ore products for their common export markets. Returning to the coal side of the business with Anglo Coal following a five-year sojourn in WA with Hamersley Iron, has provided the opportunity for comparing and contrasting some of the key synergies of the supply chains of both bulk commodities.Comparisons include consideration of things like: resource evaluation (especially quality aspects), run-of-mine handling and preparation, beneficiation, product handling and transportation, quality assurance and customer awareness, value-in-use and impacts on iron and steelmaking, and supply chain environmental aspects.Inherent within these are several other notable contrasts including: æseamsÆ and æorebodiesÆ, rocks and minerals, rejects and tailings, oxidation and weathering, suppliers and users, and marketing and purchasing, to name but a few.This paper covers some of the more interesting of these synergies and raises some potential opportunities for sharing knowledge and innovation between the two areas of activity in the future.

Jan 1, 2005

By Shoobridge PH, Firkin GR

The Imperial Smelting Process blast furnace (ISF) of the Sulphide Corporation Pty Limited zinc/lead smelter at Cockle Creek, New South wales, has in recent years greatly increased its consumption of low grade feed materials, and as a consequence has experienced periods of unstable furnace operation. Routine examination of production sinter, including softening characteristics and micro- examination, showed that the problems had been caused by an increasing silica content in sinter. The silica entered a low melting point glass phase containing calcium and lead oxides. The relative volume of this phase increased until it formed a continuous matrix in the sinter structure and this made the sinter more likely to soften at lower temperatures. Premature softening caused loss of operating stability in both the shaft and hearth of the ISr. The required sinter structure for ISF smelting was found to consist of a network of intermeshing, refractory crystals which provided skeletal strength for sinter lumps even after the glass phases had begun to soften and melt. With an understanding of the importance of microstructure and softening temperature of zinc/lead sinter and the progressive identification of those factors in sinter production which affect the microstructure, a significant improvement in stability of operations has been possible.

Jan 1, 1980

By Smith DM Jr

Silver deposits, in which silver forms at least fifty percent of the value of the ore, are abundant and large on the east side of the Pacific and are absent in the western Pacific. To determine if this uneven distribution is related to features of consuming plate tectonic boundaries which dominate the metallogeny of the Pacific Rim, the variation of Ag/Au in porphyry copper deposits was used to estimate the relative silver content of magma generated in subduction zones. Porphyry copper provinces with high Ag/Au occur in regions of the eastern Pacific where silver deposits are abundant, suggesting that the distribution of silver deposits is controlled by the relative abun- dance of silver in subducted ocean crust. Ocean crust being subducted in the eastern Pacific is mostly less than 50 million years old in contrast to most ocean crust in the western Pacific which is much older. Enrich- ment of silver in young ocean crust at spread- ing centers may reflect metallogenetic evolution over geologic time. Silver may be transported to the surface in volcanic rocks, and deposits are common where felsic varieties are abundant. The high ,solubility of silver in natural waters provides a natural storage mechanism for silver weath- ered from these rocks and ultimately circulated in near-surface hydrothermal systems where many silver deposits form. The regional distribution of silver deposits is not influenced by discoverability, vertical metal zoning, or regional tectonic style. The effect of igneous differentiation is unclear.

Jan 1, 1987

By G Gibson, B Bessen

In coal preparation, large dense medium cyclones (DMC) at low pressure heads (typically 9D where D = cyclone diameter) are the norm. This contrasts with high density mineral applications where, largely for historical reasons, smaller cyclones at high heads are the standard. There are advantages in preferring large diameter cyclones at low heads, assuming that metallurgical performance does not suffer significantly. These include simpler plant layouts, easier maintenance, smaller spares inventories, reduced wear, reduced medium pumping demands, smaller buildings and overall lower capital and operating costs. In 2008, therefore, Xstrata Zinc decided to trial a single DSM-design 800 mm cyclone in one of its four DMC lines at Mt Isa, replacing the four 400 mm cyclones previously installed. Circumstances allowed a low head of 9.5 D to be trialled, compared with the existing 400 mm head of 21.5 D. This paper describes the trial, including tests using painted ore particles as tracers, estimates of yield and metal recovery, and wear monitoring. The larger unit performed well. There was no evidence that metallurgical performance in terms of metal recovery and waste reject rate suffered, and there was some evidence that it may have improved. Cyclone life increased, and preliminary data suggest that the replacement cost of the 800 mm cyclones is less than half that of the 400 mm units, and this is expected to improve. The plant layout and operability have also improved significantly. Xstrata has therefore decided to convert the whole plant to four low head 800 mm units, replacing the original 16 high head 400 mm units. The paper includes an explanation of the effect of static head on DMC separating force. It also reviews earlier research on diamond applications, and applies a general DMC process model to the Xstrata case, both of which confirm that large, low head cyclones are appropriate in mineral applications, contrary to conventional practice. Such units could significantly reduce both the capital and operating costs of DMC plants in mineral applications.

Jan 1, 2009

By McKew M, OÆRegan

Rapid access longwall mining' or 'longwail punch mining' is a proposed extraction method whereby longwall gate roads are driven into a seam directly from an opencut highwall. The longwall panel thus formed is retreated back to within 40 m of the highwall providing an extremely simple, reliable and therefore highly productive longwall mining system. The concept is of particular benefit for the recovery of isolated pockets of coal (adjacent to a highwall) not easily accessible from a conventional underground mine. As panel gate roads are driven directly from the open strip, minimal delays are incurred between the end of open cut and start of underground production, allowing the method to bridge the gap between open cut mining and a total underground commitment. The study was specific to the Bowen Basin, and given the likely conditions, no significant operational or geotechnical hinderances to the concept could be identified. It was therefore concluded that longwall punch mining would not expose the operator to any additional risks above that normally associated with the introduction of longwall mining. Thus, longwall punch mining is an attractive option, both operationally and financially, for open cut mines reaching their maximum economic Death.

Jan 1, 1988

By Coombes J, Richards W. L

The objective of this paper is to illustrate, in a practical way, how both geologists and mining engineers can use conditional simulation to add value to their decisions. Inherent assumptions, requirements and essential components of condition

Jan 1, 1998

By J-S Zhang

In this paper, the author briefly introduces the resource characteristics of Chinese iron ore, as well as the present increasing market demand for iron concentrate. The SHP-3200 wet high-intensity magnetic separator (HIMS) is used to separate complicated weak-magnetic iron ores being composed of specularite, limonite and siderite in Jiuquan Iron and Steel (Group) Co Ltd. Some technologies have been used to improve SHP-3200 HIMS, including modifying the angle of magnetic polar from 90¦ to 83¦, cooling the exciting coils by oil instead of air, adding reverse-washing equipment to wash off magnetic particles and adjusting the tooth-space of the matrix from 5.0 mm to 3.5 mm or 2.5 mm to enhance the recovery of fine particles. It is still difficult to meet the requirement for recovering more difficultly separated iron and the demands for high-grade concentrate of iron. In order to improve the recovery of difficult-separated iron, the film-magnetic separation technique is applied into the HIMS and a new LY matrix is designed to form magnetic gradient vertically. A flowing-film feeder is also added and the feed mouth is modified to make a slurry flow formed in the form of film along the wall of matrix. The microstructure and dissemination character of the mineral particles is studied, and the specific susceptibility of the primary minerals is measured. Then the distributive characteristics of a magnetic field for the separator with film-magnetic technique and the motion of particles in the process of separation are all analysed. By introducing the film-magnetic separation technique to SHP-Φ700 HIMS, the recovery of iron can be raised from 69.45 per cent to 76.07 - 78.96 per cent with the similar grade of concentrates of iron. Such an increase of 9.51 per cent in the recovery also shows that it is feasible for such film-magnetic separation technique to be applied into HIMS.

Jan 1, 2005

Gold mineralisation at the Macraes Gold Project is hosted in the Hyde-Macraes shear zone and can be traced for ~30km along strike, although economic resources are confined to a 7 km section in the vicinity of the Macraes township. The shear zone, which typically dips at a low angle (~20 o ) to the NE, is bounded by an upper hanging wall shear and a lower footwall fault. Mineralisation occurs along the hangingwall of the shear zone as well as in low angle concordant shears and stockworks. Ore types include graphitic cataclasites with variable amounts of quartz veining, ælode schistsÆ and quartz-vein stockworks. Rehabilitation at the mine has focused on creating an environmentally benign site dominated by pasture to allow continuation of the traditional pre-mine farming economy. Changing regional economics, continued urbanisation and a reduction in traditional employment opportunities has seen a rethink in the long-term rehabilitation outcomes. The community has recognised that the rehabilitated site will provide the basis of a viable tourism venture and the creation of a Heritage and Art Park (working title æGolden Point ParkÆ) is the culmination of that process.

Jan 1, 2002

High pressure (-1.2 GPa) Early Cretaceous granulite facies orthogneisses in Fiordland, New Zealand are in tectonic contact with a cover sequence comprising mid-Palaeozoic amphibolite facies metasediments, subordinate metavolcanic rocks and syntectonic granitic orthogneisses. This cover sequence and the underlying granulites constitute upper and lower crustal plates of a mid-Cretaceous metamorphic core complex whose emplacement was linked to continental rifting and the Late Mesozoic breakup of the Pacific margin of Gondwana. Exhumation of the lower plate granulites occurred in two stages. The first stage was associated with extreme attenuationand tectonic denudation of the cover sequence accompanying emplacement of the core complex, leading to rapid uplift of the granulites but without generating the large volumes of Fiordland-derived sedimentary detritus normally expected if uplift and erosion were the only factors involved in unroofing the granulites. Final uplift and exposure of the granulites at the surface occurred mainly during the last 10 Ma in response to transpression across the mid-Tertiary Alpine Fault and/or the obduction of Fiordland continental crust over oceanic crust of the Tasman Sea.

Jan 1, 1990

By Glaessner M. F

The island chains of the Western Pacific (Fig. 1), on account of their related origin, and the similarity of the rocks that compose them, constitute in the main a most homogeneous mineral province. They lie in a complex "mobile" zone of the earth's crust, that formed a geosynclinal area separating the continental margins of Australia and South-Eastern Asia (the so-called Sundaland) from each other, and from the margin of the Pacific Ocean proper (FIg. 2). The whole region was drowned at the close of the Ice Age, as a result of the rise of sea-level that accompanied the melting of the great ice caps in the polar regions, leaving only the higher portions as islands and peninsulas, many of them separated only by shallow seas or "shelves."The geosyncline was infilled with Mesozoic and Tertiary sediments that have undergone varying intensities of folding and metamorphism, and has been subject to intermittent periods of volcanic activity, continuing into the present. Midway between the two continental margins there is a narrow belt of pronounced negative gravity anomalies, with an extraordinary S-shaped convolution in the vicinity of the Banda Sea and Celebes, that marks the core of this unstable region. The folding within the "mobile" zonetrends parallel to it, so that the islands in its vicinity, which are regions elevated by folding, are all elongated in the strike direction of the folds. This explains not only the linear shape of Sumatra and Java, but the arc of islands enclosing the Banda Sea, and the peculiar shape of Celebes.Parallel to the belt of negative anomalies, at a close remove from it, is the line of Recent, or active volcanoes, that extends along the whole length of Sumatra and Java...

Jan 1, 1947

By S Sabanov

Supplementary sampling of particulate mass concentration, the number concentration and the average particle diameter of nanoparticles using a TSI Dust-Trak DRX Aerosol Monitor, Naneos Partector 2 has been conducted. The aim of this study was to evaluate suitability of the instrument for long-term monitoring of diesel particulate matter (DPM) at conditions of polymetallic mines. Sampling was conducted in an area of the active ore heading, requiring the use of a diesel-powered face haul-age loader R1700 and a mine truck Caterpillar AD-45. The sampling was done for 126 minutes at a distance of 30 metres from the mine face. Results of this field work can be used to expand the sampling program to other mines. Expected outcomes of this study are to develop costeffective DPM control strategies, improve mine ventilation, and protect mineworkers’ health.

Oct 12, 2022