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Rare-earth permanent magnetic roll separators, pioneered by our group a few years ago, have distinctly different operation characteristics compared to prior art electromagnetic separators of various types. Many new applications for dry high-intensity (or better: high-force) magnetic separation have been developed in a short time period. It has also been found that the new generation of separators generally are more efficient with regards to removal of weakly magnetic contaminants in glass and ceramic raw materials with minimum loss of valuable product compared to induced magnetic roll (IMR) separators.The latest development is in the area of production of clean magnetic concentrates at high recoveries. It is likely that the PERMROLLR magnetic separator will replace cross-belt and lift-type magnetic separators as a result of this most recent advance.The paper will review the features of the PERMROLLR magnetic separator in comparison with other types of magnetic separators on the market and give examples on applications.

Jan 1, 1990

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

Parallel lenticular orebodies occurring at the C.S.A. mine of Cobar Mines Pty. Ltd. are mined by mechanized cut and fill stoping over the full strike length. Access is provided for each stope lift from an inclined drive adjacent to the orebody. Mobile drill jumbos mounting hydraulically-operated booms are used for drilling upholes which are subsequently charged with ANFO explosive.Close control of drilling has been found essential for good back conditions and to ensure optimum fragmentation.Broken ore is transported from the face to the main ore pass by rubber-tyred, diesel-powered, load-haul-dump units. Initially, the units trammed ore to the main pass via the incline drive. As the stopes advanced and the lead distances increased, stope passes were developed in the wall rock and raised concurrently with each stoping lift. The passes terminate in drawpoints and production loaders are used to transport ore from the drawpoints to the main ore pass system.Two parallel ore pass systems have been developed to cater for both copper and copper-zinc ores. These systems terminate above a 48 in. by 60 in. jaw crusher. The crushed ore is conveyed to a traversing rock box and thence to one of two crushed ore bins adjacent to the main hoisting shaft. A loading station conveyor is interlocked with the winder to provide automatic ore hoisting.All phases of ore handling have been mechanized as completely as possible. Results to date indicate this policy has been vindicated but highlight the need for tight operating control and close liaison between operating and maintenance personnel.

Jan 1, 1969

By d&apos, Alton AJ, Rigden DT

Modern petroleum refining offers a complexity of environments, each requiring different metals for the satisfactory performance of-the various sections of the refinery, and this paper first outlines the varied enva.x¦on-ments thus met.It follows that the metal types in use will also vary to suit each particular environment, and the paper' consequently covers the use of ferrous-metals, ranging from plan carbon steels to the high alloy types and the non-ferrous metals, particularly copper and its alloys.The failures of some,of these metals and alloys are then illustrated by experiences it Kwinana. These failures are duo to (a) corrosion, (b) erosion, (c) faulty welding, and (d) mechanical defects,' of which the first is by far the most prevalent. The protective measures taken to prevent subsequent failures are then given under one or other of the following headings :(1) alterations in process conditions, (2) the use of alternative ,alloys,(3) suitable heat treatment, (4) redesign of the failed section, (5) cathodic protection, and (6) use of corrosion inhibitors.Reference is then made to the use of specialised metals and alloys.Metals, generally in the form of oxides or salts, are also used as catalysts in refining processes. Activated alumina is used, combined with silica .forScracking' of heavy oils, and as a support -for platinum, cobalt, molybdenum, nickel and similar metals, which catalyse hydro-genation and dehydrogenation-processes. .In the final formulation of petroleum products metallic compounds may be added. Reference is made to the large quantities of lead used by the petroleum industry and to the use of metallic soaps and detergents in the formulation of lubricating oils and greases.

Jan 1, 1962

By Z W. Orndorff

Excavation through sulfidic geologic materials during construction activities has resulted in acid rock drainage (ARD) related problems at numerous (>40) locations across all five geologic regions of Virginia, USA. Potential acidities ranging from >100 to develop a statewide sulfidic materials risk map; document ARD impacts to soil and water quality and engineered structures; and develop methods to assess site-specific risk potentials within a given highway corridor. A statewide sulfidic materials GIS risk map was developed based upon the state digital geology map which assigned four levels of relative risk to all mapped strata based upon predicted lime requirements and probabilities of encountering highly reactive materials. Non-highway construction activities have also routinely disturbed sulfidic materials, and a recent airport project in northern Virginia resulted in over 150 ha of extremely acidic (pH 45 mg/L) run-off from this site heavily damaged a receiving stream, partially due to the fact that it dissolved the galvanised steel water control structures in stormwater detention basins, leading to direct discharge of run-off and sulfidic sediments. The airport area was treated and revegetated in 2002 with a combination of lime-stabilised biosolids, straw mulch, and acid-tolerant grasses. Water quality in a receiving second-order stream quickly responded to the treatment, but some release of N was also noted as a secondary effect. Collectively, these results point out the importance of accurately assessing the potential for excavation of sulfidic materials in construction environments, and the necessity of developing toxic materials handling strategies similar to those employed in mining environments.

Jan 1, 2003

When a thin film of volatile matter is deposited under vacuum on a polished coal surface, and the coated surface is examined microscopically in piano--polarized reflected light, colour changes are observed characteristic of the various macerals present. The colour changes appear to be mainly due to interference between light reflected at the upper surface of the film and at the film/coal interface. A variety of source materials for the volatile matter required have been tested, including powdered bituminous coal, coal tars, boron oxide, and certain resins.

Jan 1, 1969

TABLE OF CONTENTS:Introduction.Chemical Composition-lignitic coal-earthy coal-pollen coal-fern coal-nature of ash in the several coal types.Carbonization Tests.Air Drying of the Coal Types-rate of drying in the coal face-relative rates of diffusion-differential slacking of coal types-rate of oxygen absorption.Origin of the Coal Types-colour difference-cause of different rates of diffusion.Practical Significance.Summary.Acknowledgments.The Yallourn brown coal seam, where exposed in the Yallourn Open Cut, and the Latrobe brown coal seam, where exposed in the Yallourn North Open Cut, are both distinctly bedded. Close inspection shows that both seams consist of beds of coal from 1 to 10 ft. thick, which on drying out develop differences in colour and in their, shrinkage crack patterns. Tliese differences become apparent in the...

Jan 1, 1947

By O&apos, Malley G. B

The properties of bearing metals are of considerable interest to mine engineers, since continuous running of mine and mill machinery is of vital importance. Of the several available types of bearing metal, the low melting point lead or tin base alloys are most generally used in mining plant because of the ease of replacement and the possibility of remelting scrap metal from old bearings. The most valuable property of these "white metals," however, is the plasticity which gives a self-aligning character to the bearings, enablingthem to adjust themselves to inequalities which may exist at the time of fitting, or which may develop during running. The object of the present paper is to explain in general terms the physical structures of white bearing metals, and to point out that constitution rather than composition determines the physical properties of these alloys. The same, indeed, is true of most engineering alloys. In steels, for example, a change in the structure may affect the properties to a far greater extent than a change of chemical composition.Structural changes in steels are produced chiefly by heat treatment. In the case of bearing metals no good purpose is served by heat treatment; the microstructure is determined by the conditions of casting, and striking differences in constitution (and therefore in properties) are encountered in an...

Jan 1, 1932

The price of oil and other minerals may not make the costly business of offshore exploration seem -attractive at present. There is little doubt that the future search for the strategic resources will tend towards deeper waters particularly on the continental slope margins. In addition with the realisation that active tectonic environments (eg the Makassar Straits) cannot be excluded as potential hydrocarbon sources there is an increasing demand by the explorationists for deep water survey capability. Such deep water research has until recently been restricted to a few specialised academic institutions ;however with the anticipated extra, demand from other institutions, companies, and government agencies, Marconi Underwater Systems Limited (MUSL)and the Institute of Oceanographic Sciences in the UK have come together to allow MUSL to provide the deep water mapping system GLORIA on a commercial basis -for the first time. The GLORIA package comprises a deep water(more than 400m) side scan sonar system which, by operating at a frequency around 6.4 kHz can insonify swathes on the seafloor up to 60 km wide. In addition, single channel seismic, 3.5 kHz high resolution profiles, precision echo sounding, magnetic and gravimetric data all combine to provide as complete a regional interpretation as possible. The GLORIA system combines surveying at a reconnaissance level, covering as it does up to 20,000 sq.km per day, with a very high reliability, so that even in- economically unfavourable times, it can-still be considered as an invaluable and cost effective primary exploration tool. Analysis of the GLORIA data enables the identification of areas of particular interest requiring more detailed study by the more costly multi-channel seismics at a later date.

Jan 1, 1987

By Chappel R. A, Fishburn B. R

The Eastern Distributor Tunnels - the first major road tunnel project in Australia - are the preferred solution to traffic congestion problems, when compared with alternatives, in this inner urban environment. This is because of the reduced impact on residential housing, the improvement of the existing environment, less restrictions on future developments, and a reduction in noise and pollution. Developments leading to a tunnelled solution, traffic needs and reasons for route location are discussed. Criteria for design of tunnel alignments and geometry are described, including the restraints imposed by surface connections on profiles and grades resulting in low rock cover at tunnel portals. The main geotechnical restraints are a major weathered dyke at the shallow large span underground fork and the weathered Ashfield Shale capping the Hawkesbury Sandstone at a portal. Rock cuttability and excavation methods are discussed. Roadheader machines are the most suitable for the varying shallow arched cross sections required and the tunnel lengths involved but the use of blasting in special situations cannot be ruled out. Initial support for the major tunnel lengths will be provided by rock reinforcement in conjunction with shotcrete. Steel ribs are proposed in areas of low cover and weak ground. Final support will comprise an insitu concrete lining. Construction concepts and special tunnelling methods required at the shallow underground forks and tunnels are described.

Jan 1, 1987

By S Miller, A Neale

As part of a long-term acid rock drainage (ARD) mitigation study, PT Freeport Indonesia has completed the construction of a highly instrumented, full-scale, experimental, overburden stockpile to further evaluate the behaviour of the waste rock system at Grasberg mine. A total of 24 lysimeters, 30 sets of thermistor strings and 48 oxygen-sampling ports were installed at select locations during stockpile construction. ARD flow rates and chemistry have been recorded since the start of overburden rock placement in April 2000. Measurements of in situ temperatures and oxygen concentrations quantify reaction rates and the oxygen pathways that control oxidation kinetics deep within the waste rock profile. Direct field observations show the significance of advective oxygen flow with respect to the onset of oxidation kinetics. Oxygen measurements show that the rubble zone that forms at the base of a waste rock bench provides a critical pathway for oxygen entry to the waste rock profile. Furthermore, rapid oxidation as evidenced by measured temperature increases deep within the panels of waste rock is observed to occur. The observations presented in this paper provide critical insight for understanding the mechanisms and behaviour of full-scale waste rock stockpiles with respect to ARD generation. The results of this program will assist in the future selection, testing and evaluation of appropriate mitigation measures with respect to surface and face treatments to reduce long-term ARD generation. This project is a work in progress, and at least another two-years will be required to fully understand site-specific ARD generation and ARD mitigation mechanisms. This paper will discuss various design and construction considerations, provide an overview of results achieved to date, and some preliminary interpretation of what is happening within the overburden stockpiles.

Jan 1, 2003

The Central Extended Orebody is located within the Cracow Goldfield approximately 360 km northwest of Brisbane and approximately 220 km west of Bundaberg. It is an epithermal gold deposit hosted by the Late Carboniferous to Early Permian Camboon Andesite. The lode was mined by open cut methods and produced 170 458 tonnes of ore at 5.62 g/t gold.The geology of the rit is relatively simple, comprising two rock types, trachyandesite and rhyolite which have been sub-divided into several units. The trachyandesite is sub-divided into three rock types: brecciated trachyandesite which is the most widespread, hydraulically fractured trachyandesite hosts the mineralisation and the third sub-unit is chloritised hydraulically fractured trachyandesite and has no associated mineralisation. The mineralisation is confined to quartz veins in hydraulically fractured trachyandesite. Several phases of brecciation and subsequent quartz and quartz/adularia vein injection are evident although not all phases are mineralised. Two rhyolite dykes intrude the trachyandesite one is monolithic, the other is sub-divided into hydraulically fractured rhyolite (barren), silicified rhyolite and auto-brecciated rhyolite.

Jan 1, 1993

The Fiji islands are the world's most ac- cessible Cenozoic remnant arc. They provide occasional subaerial exposures of an arc frag- ment some 750 km long and 80 km wide, or about the size of the NE Japan volcanic arc. The fragment is one part of the former Vitiaz Arc which once connected Fiji to Vanuatu and Tonga. The Fijian portion has the most completely stu- died Tertiary section which contains a history of arc volcanism from the late Eocene to late Miocene (the Early and Mature Arc stages), a rich diversity of subsequent magmatic responses to the most recent episode of arc rifting (Ear- ly Rifting stage), and an example of transition from arc to intraplate volcanism as this rift- ing proceeded (Late Rifting stage). The arc fragment is surrounded by younger backarc ba- sins. The chemical composition of magmas in both the arc and backarc changed with time, but in opposite directions. In the arc, magmas be- came enriched in sialic components from the Early Arc to Early Rifting stages, whereas in the basins the magmas became more similar to mid-ocean ridge basalts (MORBs) with time. In southwest Fiji, the oldest backarc basin has subducted obliquely beneath the remnant arc du- ring the last 3 Ma, resulting in chemically ex- otic calcalkaline volcanism. During the last decade over 150 radiome- tric age measurements and 650 rock analyses, many with trace element and isotopic measure- ments, have been obtained for samples from Fi- ji, Tonga, and the surrounding seafloor (Figs. 1 and 2). These data are summarized, drawing from the publications of Colley and Hindle (1984), Gill et al. (1984), Hawkins and Melchi- or (1985), Kroencke (1984), Malahoff et al. (1984), Scholl et al. (1985) and Whelan et al. (1985), from the specific research papers refe- renced therein, and from the half dozen or so manuscripts currently in preparation by these people and others.

Jan 1, 1987

By Likar J, Janexic S, Zigman F

When driving mine roadways in the vicinity of tectonic disturbances and fault zones, sudden outbursts of gas, along with ejections of fine coal, occur. Substantial dynamic changes occur around the roadways in the coal and around the support. The problem has several aspects. Studies have been carried out on the technical analyses of the phenomena which occurred in the Velenje Lignite Mine from 1957 to 1988. The second part of the investigation involves systematic laboratory studies of strength and deformability characteristics of lignite samples and "in-situ" measurements of stress changes during the driving of some roadways. Analyses of events (using the model of limit convergence and the finite element method) showed the possibility of gas outbursts, taking into account the deformability conditions when crossing over from compact lignite to the disturbed region. The rate of advance of roadways and the method of support strongly influence the occurrence of the phenomenon. The preventative measures used in driving roadways under such conditions include trial drilling and the use of blasting instead of machine cutting.

Jan 1, 1992

By McOnie A. W, Rutherford PG

A volcanic sequence is described from the Golden Cross Mine, Waihi, New Zealand. The sequence includes seven lithostratigraphic units comprising flow and pyroclastic units of Coromandel Group andesite and dacite and overlying Whitianga Group dacite and rhyolite which is intruded by the Golden Cross dacite porphyry and rhyolite dykes. The sequence is mineralized and is unconformably overlain bv_ two post-mineral units, the lacustnne Waitekauri beds and Omahine Subgroup andesite. Detailed structural analysis of mine data has identified four deformational events (D 1-D4) and related these to the gold-silver mineralizing events. Faulting was coeval with the mineralization and directly controlled the development, localization, style and geometry of the ore shoots. Mineralization developed in competent lithologies where dilation occurred during faulting. The Empire Fault is the master shear which controlled fluid flow. Mineralized veining developed in response to tectonic pulses occurring at slightly different stages as represented by the underground Empire vein complex and the open pit vein array. The mineralizing events culminated with the deposition of barren calcite veins. Post-mineral movement along the Western Boundary fault appears to have offset the ore body.

Jan 1, 1995

By Lee M. F, Guilfoyle K

A large hard rock rib pillar was recently preconditioned at Mt Charlotte mine using a novel blasting technique. The motivation for trialling this procedure was a history of past pillar failures, with associated seismicity. Design studies had shown that a new proposed pillar would be at risk of violent failure, and preconditioning was used in an attempt to reduce this risk. Preconditioning by blasting involves physically modifying a selected zone of ground in advance of mining, then forming the pillar so that it incorporates that zone of ground. The modified rock in the zone is intended to allow extra closure (yield) of the pillar in response to mining-induced stress changes. The ground modification was done by tight firing a blasthole array to fracture the rock. The blast design comprised pairs of pre-split blastholes to create a series of short cracks across the target zone, followed by main blastholes to fracture the rockmass between each pair of cracks. A monitoring program was used to establish whether or not the preconditioning was effective. It included conventional extensometers, stress change cells and closure stations, plus a seismic monitoring system. To-date, stoping is complete on one side of the pillar and has just commenced on the other. Results show significant movements within the preconditioned zone and on geological structures in the pillar, as well as lower stress in the pillar compared to an adjacent non-preconditioned site. The preconditioning technique can be applied elsewhere, provided its purpose, mechanism and side effects are understood. Benefits are likely to include more assured production, and successful pillar recovery even in high stress situations.

Jan 1, 1995

British Coal has made a practical progressive approach to improving the reliability of its mining equipment. Reliability must be addressed at the specification stage but does not end there and routine procedures are used to procure equipment of adequate reliability. The techniques used to monitor and improve reliability during the operational phase of the equipment, providing engineers and operators with detailed printouts, together with the types of maintenance employed, ensure high levels of availability. Finally, the methods of repair and overhaul of British Coal equipment and systems ensure that the initial reliability targets outlined on the specification, can still be achieved.

Jan 1, 1991

It is often assumed that geotechnical investigations or studies for open pit mines are confined to providing a slope design. However in an operating mine, the design is only one component of a mine geotechnical program. Reviews of slope designs are ongoing throughout the mine life. The concept of Pit Slope Management has been formulated because the design only entails one component of a total program that contributes to a safe, efficient mining operation. Risk is a normal part of mining. Effective management allows the risk to be contained or controlled. If the slopes are not effectively managed there will be increased risk for the operation. Experience has shown that utilisation of Pit Slope Management coupled with a broad base of experience to define the key controls on stability, provides a pro-active, objective approach. The reasoning is deductive and relies on the behaviour of the ærocksÆ. Once the key aspects are defined, studies are well focused, implemented as required and the risks can be effectively managed. When the key controls on stability are poorly understood reasoning is typically more ægut feelÆ. Under such circumstances studies, if carried out, may meet short-term objectives but often ignore the long-term objectives. Hence the risk to the project is greatly increased. This paper presents several case studies highlighting the above aspects and present elements of the Pit Slope Management Program approach which have been successfully utilised by the author to manage risk in mining projects.

Jan 1, 2003

By Nilmani M, Fountain CR

Injection of gases into slag-melt mixtures produces various zones as a result of bubble formation and disintegration within the melt. The extent of these zones depends on the type of reactor used. When compared with ferrous processes, non ferrous processes are character- ised by large bubbles formed adjacent to the tuyeres, low flowrates and shallow tuyere sub- mergence. These features can result in a greater proportion of reaction occurring above the bath, more refractory wear and tuyere blockage with more splashing. The large bubble zone adjacent to the tuyeres has been investigated using the tech- niques of physical modelling, mathematical modelling and plant trials. Large bubble form- ation in physical models was recorded using a high speed camera and a rapid response pressure transducer coupled to an oscilloscope and data recorder. It was found that the bubble volume (Vb) could be correlated at low flowrates using the single bubble model Vb = 1.378 Q6/5 g-3/5 Deviations from this correlation occurred with increasing gas jet momentum. Plant trials were carried out on a copper converter at Mount Isa Mines during five different charges. Pressure measurements were made through the tuyeres during the slag blow and commencement of the copper blow. The power spectrum density showed that the dominant pulse amplitude occurred at a frequency of approximately 3 pulses/sec. Plant data from this and other converters were correlated using the same relationship as for physical modelling. De- viations occurred due to the state of the re- fractory, bath composition or bath circulation effects.

Jan 1, 1984

Competitive commercial circumstances internationally provide a prime impetus for miners to seek new technologies as a means to profitability and survival. Engineering and project management activities play a vital role in establishing, operating and developing the capital facilities used by miners. Computer based technologies are the single most important technology for maintain- ing competitiveness in engineering and project management into the future. Current applications of computers in engineering design and drafting are finding economic applications, computer-aids are more readily introduced, accepted and profitable. Computing technology is advancing very rapidly and on a broad front in hardware, software and communications. This technology advance is improving the ability of engineers and project managers to provide a high quality, responsive and low cost service which will improve in parallel with computer technology. As this technology advances, a key challenge is created for managers in selecting hardware and software, in developing people and organisations and in marketing the technology to advantage. While the future holds many exciting developments, people will still hold the key roles. While the nature of their roles may change, the final acceptance or rejection of technology will be by people, whether as users or owners, who will judge on the basis of whether their stake is improved or not.

Jan 1, 1986