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By Low Russell

Mark Westfield, writing in The Australian on 16 May 1994 stated: The role of the independent expert is crucial to Australia's investment system. When it falls down, there can be very dramatic consequences. The scope of these consequences was dramatically illustrated in the decision of Rogers J. at first instance in Cambridge Credit Corporation v. Hutcheson (1983) 8 ACLR 123 when the auditors of the failed company were found liable for breach of contract and faced a damages award of $145 million, well in excess of their insurance cover. No comfort should be sought in the fact that this decision was overturned on appeal, for the result of the appeal rested on whether there had been a causal connection between the breach of contract which had occurred and the loss suffered, rather than on the fundamental principle of auditors' liability. Thus: Those who prepare experts' reports in company cases carry a heavy moral responsibility, whatever their legal duties may be... Unless high standards are observed by those who prepare these reports, there is a danger that systems established for the protection of the investing public will, in fact, operate to their detriment through reliance placed on those reports and on the reputations of those who furnish them. In lending his name, the expert will often, as in this case, be lending a name to conjure With.

Jan 1, 1995

By S Basu, S L. A Gowravaram

CaF2 has been a common constituent in a wide variety of welding fluxes, including those used for submerged arc welding (SAW). The widespread use of CaF2 stems from its role in lowering the liquidus temperature as well as the viscosity of the molten slag that covers the weld pool. However, the harmful effect of fluoride evaporation from molten flux, on the environment as well as the health of the users is becoming increasingly evident over the years. This has led to increasing attention towards reducing the CaF2 concentration in the fluxes. The fluoride-free formulations face the challenging requirement to maintain the thermo-physical properties (viscosity, liquidus temperature etc) like those observed in fluoride-containing fluxes. In the present work, three fluxes with compositions in the CaO-MnO-SiO2-Al2O3 system have been identified as promising alternatives to the CaF2-rich fluxes. However, the thermo-physical properties of any such flux need to be comparable to CaF2-based commercial SAW fluxes before it can be adopted for regular use. The single hot thermocouple technique (SHTT) has been used by several researchers in the past as a tool for observing the melting and solidification characteristics of fluxes. This device has been developed in the present work and is used to characterise the melting behaviour of the fluxes. The measured solidus and liquidus temperatures from SHTT were compared with the results from differential thermal analysis (DTA) and simulations using the FactSage™ software for a comprehensive understanding. In spite of having a slight deviation in the measured values from the multiple techniques, the results obtained from these multiple methods show that the selected compositions could be potential CaF2 free alternative welding fluxes.

Jun 19, 2024

Cable bolts are being used more extensively by the mining industry for many different rock reinforcement applications. The configuration of these bolts has evolved over the last 20 years to meet the immediate needs of industry at the particular time. Most improvements to date have focussed on increasing the mechanical performance with little attention given to issues such as ease of handling, matching response to that of the rock mass or corrosion protection. Ultrastrand has been designed and being developed with this broad perspective in mind so that it will satisfy the ground reinforcement needs of today's and tomorrow's mining industry.Laboratory tests on Ultrastrand prototypes have confirmed that mechanical performance is superior or equivalent to Standard and Birdcage Strand respectively. Preliminary discussions have been held with an installation equipment manufacturer with a view to conducting a trial at a mine site by early-1992.

Jan 1, 1992

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 Gonzalez JM

The Pao gold prospect in N. Luzon, is an example of a high sulphidation epithermal gold system hosted in Mid-Tertiary alkaline volcanics, in the Philippine Arc. Styles of mineralization include: quartz-enargite veins, vuggy silica alteration bodies, and pervasive low grade (0.5ppm) gold mineralization, associated with kaolinite-pyrite-quartz alteration, and geochemically characterized by high As and Hg. Early magnetite-epidote-chlorite alteration linked to an unexposed granitoid is overprinted by an extensive zone of advanced argillic alteration (kaolinite-pyrite-quartz). No alunite is recorded. Important controls of mineralization include; a broad anticline intersected by axial faults, permeable pyroclastic units, and upward confinement of the alteration system by a highly impermeable, clay-rich volcanic unit. At this stratigraphic position the most important mineralization waz developed. The Pao high sulphidation system is not closely related to a stratovolcanic centre, and has formed subsequent to deformation of the volcanic field. It may, however, be related to an unexposed comagmatic intrusion.

Jan 1, 1990

Wire rope, when used for hoisting on a mine is the weak- est and most vulnerable unit in the most expensive'-group of installations or! the mine. With the introduction' of hoisting on the S1Koepe"' sheave, a new technique was-established. This innovation brought with it the certain- advantages which long had been recognised and which are being developed further. For many years, drum winders of many types had been the sole means by which ore had been hauled from mines. This type of winder, with its capacity for rope storage on the drum, permitted mine operating personnel to cut short lengths from

Jan 1, 1964

This paper describes the application of the Total Productive Management (TPM) technique as a performance improvement initiative for a coal mining operation. It discusses the objectives of TPM, with the driver for improved production performance being the Overall Equipment Effectiveness (OEE) of the equipment or process, and with the development of "ownership" as the behavioral approach to equipment management and continuous improvement through cross-functional and area-based teams. It illustrates the concept of equipment management as defects management.The scope for application of TPM to the coal mining industry is immense. The harshness of the operating environment can be a major generator of equipment defects, and a current paradigm in the industry accepts these defects as an unavoidable outcome defining maintenance costs in this environment. However recent benchmarking studies have highlighted that maintenance costs per operating hour in some mining operations are more than double the vendor's estimate of "best practice". The paper refers to these studies which also compare maintenance costs of fixed and mobile plant and equipment to "best practice" outcomes in comparable process industries.

Jan 1, 1998

By Mousset-Jones P, McPherson M. J

Underground airways are characterized by irregular shape and uneven surfaces including large-scale natural roughness, fractures, and a super-imposed sand roughness. Swirls in the grooves of the wall and separation because of the periodic variation of the open cross sec- tion, due to the blasting patterns, make it almost impossible to calculate average con- vective heat transfer computationally on the bases of the geometrical description of the surface. However, dimensionless friction factors can be used to characterize the surface effect of an airway and an analogy between heat and momentum transfer can be applied to calcu- late an average convective heat transfer Coefficient.

Jan 1, 1988

The paper first outlines the conceptual basis for evaluating and controlling geological risk. Geological risk, the economic reflection of the uncertainties associated with tonnage, grade, and other pertinent deposit parameters, is evaluated in terms of economic risk criteria. Delineation provides the deposit information required to appraise and control this risk. The improved reliability of geological estimates resulting from additional delineation reduces the economic risk associated with mine development and production decisions. However, the benefits of delineation, subject to diminishing returns, have to be weighed up against the direct and time costs involved. These costs decrease base case economic values and shift the probability distributions of possible outcomes towards, lower values. The optimum amount of delineation normally is achieved short of the point where economic risk is minimised, depending on the mining company's relative preference for a higher base case value or a lower economic risk. Then, two open pit copper mine examples, based on actual situations, are analysed to illustrate the application of the concepts presented. The first case concerns the extension of ore reserves at an operating mine. Finally, a new mine development opportunity is considered.

Jan 1, 1994

This paper discusses design concepts in planning a large modern bulk terminal. The need is emphasised for a studied master plan, in-built materials handling flexibility and staged development. An integrated approach is advocated, combining functional purpose designed foundations and structures to serve their mechanical, electrical and environmental functions. Dry bulk and slurry handling are also compared in perspective.

Jan 1, 1983

Copper entering a lead ,smelter in concentrate or from other sources is recoVered as matte and speiss which contain appreciable quantities of lead. The matte and speiss are usually sold to copper smelters to recover the copper content and also any gold and silver in these products, but the value of the lead is largely lost. Some copper plants pay for portion of the lead content, but regarded as a means of recovering lead it is more costly and less efficient than if the lead were recovered at the lead smelter.Because of the value of this lead loss, the metallurgy of copper recovery has assumed greater importance in recent years owing to the rise on the price of lead.Two processes are in use today to produce matte and speiss, namely the iron matte process and the soda matte process developed by the American Smelting and Refining Co. 1 in D.S.A. The latter process is characterised by a higher copper to lead ratio than the older iron matting process.The following analyses are typical of matte and speiss produced at Broken Hill Associated Smelters, by both processes, although the soda matte process is still in a developmental stage and experience indicates that matte and speiss of lower lead tenor can be produced under favourable conditions.

Jan 1, 1951

Extensive reserves of kaolin of the type suitable for use as a high quality paper coating exist on the Weipa Peninsula. In 1986 a commercial processing plant was constructed to produce 100 000 tonnes per annum of coating quality kaolin targetted principally for export. A number of processing difficulties have limited the production capability of the plant. The prime area being the pressure filtration operation with achieved cycle times being around 50-60% of design. The rate determining steps being press filling, press unloading and filter cloth washing. This paper details and summarises testwork and results from our attempts at decreasing the filtration cycle time.

Jan 1, 1989

Tumbling mills have been used in the minerals indusu) for occr WO years, with the design changing little, but the size of the individual pieces of equipment increasing significantly with the lowering of head grades, and the push for greater

Jan 1, 1997

By P Marlow

Raiseboring is an attractive method of constructing shafts, being safe, fast and comparatively cheap. But this means back-reaming through weathered ground. However in the gravels and weathered near-surface rocks typical of the Western Australian goldfields, back reaming large diameter shafts through to the surface is risky and conventional sinking from surface has normally been required.An alternative construction approach has recently been used to stabilise the weak surficial materials and allow raiseboring through to the surface. The method is based on first installing rings of non-contiguous reinforced bored piles around the shaft perimeter, for temporary support, then back reaming shafts at full diameter through to the surface. Immediately after the reaming head is removed, the weak exposed materials are supported using remotely sprayed fibrecrete.The method has been successfully applied to four shafts since July 2007; 3 m and 4 m diameter shafts at Trident Mine, a 3 m diameter shaft at Wattle Dam and a 4.5 m diameter shaft at Athena Mine.Bored pile layout designs have varied from eight to 24 piles, of diameters 120 to 270 mm, in one or two rings. In one case, the top 10 m of the proposed shaft was pregrouted. Subsequent surveys have confirmed that fallout occurred in some shafts, out to the ring of piles, implying that the piles inhibited collapse.The practical implementation of the method was not always easy and many valuable lessons have been learnt. This paper documents key aspects of the method and the critical elements for its application.

Mar 21, 2011

The pilot scale testing of Australian coals for their NO, emissions was carried out at the ACTC to investigate the influence of coal properties, furnace conditions and different NO,, control strategies on NO,, emissions. The NOx emissions for the Australian coals tested were found to vary over a wide range and primarily depended on combustion temperature and excess oxygen conditions. These coals did not exhibit any fundamental difference in NOx levels to other world coals. Under similar combustion conditions, the conversion of coal nitrogen to NO. was found to be best correlated with coal rank parameter, R, max per centage. The use of staged combustion as a control strategy was shown to reduce their NOx levels by 56 - 77 per cent.

Jan 1, 1991

Geological hazards such as faulting, basement ridges, and zones of "thin" (

Jan 1, 1998

By Quast K. B

The effects of metal ion addition rates and contact time on the activation of synthetic sphalerite using copper, cadmium and silver ions were determined in order to investigate the exchange characteristics at the mineral surface. The stoichiometry of the adsorption indicated that the activation of sphalerite involved both a simple ion exchange and redox process in which the activating ion and oxygen were reduced, and the mixed-sulphide surface was oxidised to produce elemental sulphur and a metal-deficient sulphide surface. Unactivated sphalerite was shown to be relatively hydrophilic, with recoveries usually less than 20 per cent for a five-minute float. Activated sphalerite could be readily floated without the use of a conventional collector. This inherent flotability of the activated sphalerite had previously been associated with the formation of a metal-deficient sulphide layer; however, this study emphasizses the significance of the surface oxidation processes occurring.

Jan 1, 1993

For the past five years the University of Queenslandhas, through its various workshops, been preaching to Australia that there was a potentially hazardous situation from earthquakes for urban Australia. A few people outside The University accepted this, but largely the warnings fell on deaf ears.The 1989 Newcastle earthquake changed that per-ception. The most important lessons to emerge from Newcastle were (i)the realization that in continental areas small earthquakes cause widespread damage:(ii)the local geology of an area is of great importance in the damage done by an earthquake.These two factors clearly indicate that, in the future, we must take far greater account of the "Urban Geology" of an area. This paper discusses the need for urban geology and its impact on seismic risk and compares that with the traditional methods of assessing seismic risk.

Jan 1, 1990

The lignite mines in the Latrobe Valley of Victoria/Australia have been using continuously operating mining systems for more than 50 years. The relatively small bucket chain dredgers of the early years have been progressively displaced by bucket wheel dredgers with increasing size, increasing capacity and increasing service weight. The large machines for the new open pit Loy Yang have a bucket wheel outreach of 46m, an effective capacity of 3350 bm' coal/h respective 2500 bm' overburden/h and a serv- ice weight of approx. 4500 t. The time between signing of con- tract and starting of operation for these machines is at least four years. The high service weight, the resulting high capital invest- ment and the long period for design, design review, manufac- turing, erection and commissioning of these machines directed the SECV to investigate a possible application of compact dredgers for the Latrobe Valley.

Jan 1, 1989

The mineral pulp as it passes through grinding-classification, flotation and solid-liquid separation is examined in the context of it being a particulate fluid. By focussing on the complex viscosity and yield stress of the fluid, new control strategies are discussed. The mineral-particulate fluid is dominatred by non-Newtonian rheology (ie shear thinning, shear thickening, shear yield stress and compressive yield strength). The control of this Theology is seen to be dependent on the fundamental practice-particle interaction forces and with adequate information, it is possible to use the complex shear properties to advantage. The advantages, in terms of final waste and concentrate management, to high weight per cent solids in the mineral particulate fluid, are explored and control strategies outlined.

Jan 1, 1993