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The comparatively low winter rainfall, exposure to heavy salt laden coastal winds, and the consequent high evaporation rate, are important considerations in the rehabilitation of the Maslins Beach Sand Pit. The deficit of rainfall over evaporation is assessed at 1085 mm per annum. Such a coastal environment complicates the establishment of plants. The endemic flora found on the Sand Pit environs is mainly low wind-planed shrubs and mat plants. The dunes near the coast support an association dominated by Atriplex cinerea, Spinifex hirsutus, Scirpus nodosus, and Olearia axillaris. The coastal cliffs carry a more diverse vegetation dominated by Beyeria lechenaultii and Eutaxia microphylla. Overburden is used to develop a new landscape to screen operations, batter final faces, and cover rubbish at the nearby Council dump. The early overburden dumps were built with little regard for stability, but the more recent practice of using scrapers has resulted in more stable dumps. The erosion problems created by poor compaction have been controlled by contour banks, diversion drains, bitumen lined run-off drains, and hay mulching.

Jan 1, 1976

Methods of measuring the frictional properties of rock surfaces, both by direct sliding and in triaxial apparatus, are described. It was found that for some rocks the coefficient of friction remains reasonably constant as sliding is continued but for others it increases considerably.The effect of fluid pressure in the surface of sliding was found in all cases to be adequately represented by the effective stress criterion. Some observations on sliding on two conjugate planes showed that the motion on the two planes may be very different, depending on small differences in the constraints.The coefficients of friction of natural open joints in bore core were found to lie in the comparatively narrow range 0.32 to O.68 although surface coatings were very diverse.A set of diagrams on the equal area projection is given which enables a rapid determination to be made of those planes on which sliding is possible in a given three-dimensional stress field. The influence of the intermediate principal stress on this is of considerable importance.

Jan 1, 1969

By Lunardi P, Pelizza S

The link between the Lecco bypass and major road SS36 (Italy) requires the construction of a double two-way tunnel (through the mount San Martino carbonatic massif). The tunnel excavating section is about 90 sqm through mount San Martino carbonatic rocks. The mountain sides are unstable and are often the scene of large collapsing landslides (tens of thousand cubic metres). The tunnels are very close to the mountain sides. The use of blasting induces vibrations which may reach the Lecco built-up area. With a view to avoiding such dangers the excavating operations were carried out in two successive stages: - opening a pilot tunnel, whose section is about 10 square metres, by a full face TBM to eliminate the more intense vibrations which are generated by the first opening charges; - successive enlargement by blasting.

Jan 1, 1987

By Restarick CJ

Plant data are presented which indicate a relationship between flotation rate constants and pulp density in zinc cleaning circuits at Broken Hill. The data were obtained from down the bank sampling of cleaner and recleaner banks at North Broken Hill and New Broken Hill Consolidated Concentrators. It was found that, under normal plant operation, flotation rate constants increased at the lower pulp densities existing in the later cells of cleaner banks. The addition of dilution water to the feed to the bank increased flotation rate constants, thereby confirming the relationship. It is shown that the relationship between flotation rate constant and pulp density is size dependent, being most pronounced for larger sized particles. In contrast, the effect is not markedly dependent upon mineral type. Possible consequences of this relationship for control of cleaner operation are discussed with the aid of some simulated results.

Jan 1, 1978

By Ellis WK, Greenwood-Smith R

A nuclear technique for the analysis of copper in bulk materials has been developed and successfully field tested at Mount Isa Mines Limited. The technique utilises the gamma-ray resonance scattering process. A bulk analyser based on this technique gives a rapid and accurate measurement of the percentage by weight of copper or nickel aver- aged over a large mass of sample, typically 20 kg. The only sample preparation required for accurate analysis is crushing to -2.5 cm. At Mount Isa over 100 mineral samples covering a wide range of rock types and copper contents were analysed. Bulk analyser assays and chemical laboratory assays agreed closely for underground pillar-extraction and geolog- ical chip samples, conveyor belt samples, and finely ground samples from the ore concentrator. For the concentrator samples, the root mean square deviation between bulk analyser and chem- ical laboratory assays was 0.06 wt.% copper. The chemical assay errors for these samples were about 0.06 wt.%

Jan 1, 1975

The iron ore deposits of-the Port Hedland distract of North-Western Australia are associated with banded-sedimentary iron., formations that.form part of the local succession. of folde.d..and faulted Archaean volcanic and sedimentary. rocks., The iron formations are regarded as the pr.otore,beds or sources of.the. iron which became;.,c,o.ncentrated by supergene.,processes. to form c,omznercial grade.. iron ore deposits,, ;-ò; Iron oxide ' deposit's occurring in"situ' within' the prot'ore beds are considered to be of residual--repplacement,origin`, due to supergene leaching of gangue minerals and deposition of secondary iron oxides in their'place'. Two types of deposit have been recognized. Lode deposits are deep lenses of massive hematite located adjacent to major, fau.lts... - These; deposits are-thought-to be very.,,old' and-to: have originated by supergene processes:.. during the, long: period of_ erosion represented- by the major, unconformity between the, Archaean .rocks and the, over!.

Jan 1, 1964

The mining production rate of two million tonnes per annum at Olympic Dam required greater servicing capacity than was available with the existing Whenan Shaft. To increase servicing capability a Service Decline was constructed from June 1986 to June 1987 extending 2000 m from the surface and linking up with inclining development from the existing Whenan Shaft workings. The decline was used for access of all men and materials during the construction phase of the ore handling system. During production, most mine servicing will be via the decline with hoisting of rock through Whenan Shaft.

Jan 1, 1988

The maintenance system for underground mobile equipment at Cobar Mines Pty. Ltd. has been modified from that originally planned as a result of experience gained in operating the equipment.Downtime due to breakdowns has been reduced by improvement of vehicle servicing and overhaul procedures.Frequency of breakdowns can be reduced by training operating and maintenance personnel to a high standard, ensuring adequate numbers of tradesmen and supervisors, good maintenance facilities and communications, a well designed mine layout, and a comprehensive stock of spare parts.A maintenance and downtime summary is compiled for each four-week operating period and this is useful in highlighting particular problems where corrective action must be taken.

Jan 1, 1969

By Thompson D, Burgess G. C

Subsequent to large scale trials in 1987, the installation of a submerged lance Sirosmelt furnace system was approved in late-1988 for the cupellation of retort bullion to dore silver. Commissioning work commenced in June 1990. During the process air is lanced into a molten slag bath contained in a cylindrical vessel to rapidly oxidise the granulated feed bullion from 15 - 25 per cent silver to rough dore grade. The process is now an integral part of the Precious Metals operation replacing the first stage reverberatory cupellation furnaces to achieve productivity improvements, lower silver inventory and increased silver Recovery.

Jan 1, 1992

By M Donatelli, E Grazio, A Heissenberger

The distribution of a contaminant in a bulk mass greatly influences the effectiveness of sampling procedures. Most currently used sampling guidelines for genetically modified organisms (GMO) testing have stringent distribution requirements. Specifically, all these protocols are based upon the assumption that GM material, if present, is randomly distributed. Yet, assuming randomness is risky because the applied sampling plan may not provide an accurate estimate of the content of the contaminant. Despite the general consensus that an evaluation of the possibility of non-random distribution of GM materials within lots is a pre-requisite for the definition of effective sampling protocols, no experimental data on the distribution of GMOs in kernel lots are available anywhere in the world. Additionally, to date there is no distribution-free statistical model to estimate sampling errors, thus making the theoretical definition of optimal sampling technique impossible when randomness cannot be assumed. Here we present preliminary results of the KeLDA project, which is the first study investigating the distribution of GM materials in large soybean lots imported within the European Union. The extensive variability of GM content, observable both within and among soybean lots, indicates that heterogeneity issues cannot be overlooked when defining sampling strategies for large lots of particulate material and that randomness cannot be assumed a priori. A new statistical model free from any distribution assumptions, developed in order to estimate the sampling error associated with different sampling protocols together with the risk of false-negative results, is also presented. The new model, which is applicable to any consignment of particulate material with respect to any kind of contamination, presents two novelties: first, freedom from any distribution assumption; second, the possibility of estimating the magnitude of the sampling error associated with different sampling protocols as a function of specific distributional properties.

Jan 1, 2005

I must tell you at the outset that I come to this conference deeply disturbed at the `role of Government in international dealings in mineral and energy resources'. I am disturbed by the confusion that now passes for policy. I am disturbed by the short- range view of critical problems taken by a majority of Governments. I am equally disturbed by the even shorter range of view taken by a growing army of industries. Many of them clamour for Governments to solve their problems in a specific way, with little regard for any other sector but their own-and with even less regard for the fact that every time a Government takes over some of their responsibilities they surrender some of their freedom. I would not say that longer range views don't exist. But I would say that they don't prevail at the present time. Instead, we are seeing the con- stant development of many policies for individual problems which don't tackle the fundamental causes. We must get back to basics without delay.

Jan 1, 1978

By N Tuffs, R Peace, S Xue

Mine gas control is a major issue in most of the gassy underground coal mines, due to its direct impact on safety, production delays and cost of production. Analysis of the gas data, from different collieries in Australia showed that longwall gas emissions have increased substantially over the years. Simply increasing the number of goaf holes in the panel or decreasing goaf hole spacing seems not to be effective, in controlling high goaf gas emissions. A major research project has been undertaken by CSIRO in collaboration with mine sites to address this goaf gas control issue with the aim of developing effective and optimum goaf gas drainage strategies. The project has combined extensive field studies with computational fluid dynamics (CFD) models, to characterise goaf gas flow patterns and develop effective gas control strategies. The research work specifically involved review of gas control issues at field sites, goaf gas monitoring, tracer gas tests, CFD simulations and extensive field trials. Field demonstration studies of the new optimum strategies have been conducted at two collieries in Australia. The project results have shown that the optimum strategies were highly successful, in improving the overall efficiency of goaf gas drainage systems, at both the field sites. Results of the goaf gas flow characterisation studies and field demonstration studies are summarised in this paper.

Jan 1, 2005

By J N. Moncrieff

The resource estimation process for the underground Mount Isa Copper Mine has undergone significant change. Block models are now created using a commercial software package as opposed to the in-house software that was previously used. With mineralisation occurring over a strike length of more than 4 km, Mineral Resources for all categories totalled 190 Mt at 2.7 per cent Cu at 31 December 2002. Estimation is by ordinary kriging with two separate models generated to cover the X41 and Enterprise orebodies respectively. The underlying Upper Basement Contact and the silica-dolomite alteration envelope are both used as hard boundaries to constrain the modelling. From a validated block model, grade shells are generated at the appropriate cut-off grade for a given area. The grade shells are depleted for mined voids and subdivided into 30 metre strike length blocks. Application of a SMU criteria and crown and pillar constraints results in failed blocks being culled from the resource inventory. Mineral Resource blocks are further subdivided into resource categories (Measured, Indicated, Inferred) by the Competent Person on the basis of geological confidence, taking account of geological and grade continuity, drillhole spacing and structural complexity (JORC, 1999). A geostatistical æconfidenceÆ category is incorporated into the block model as an additional tool for the categorisation process. The shapes are assessed in concert with a mining engineer to determine whether a reasonable expectation of mining potential exists and if not they are removed from the resource. The final categorised blocks constitute the Mineral Resource inventory and form the basis for conversion to Ore Reserves. The resultant Mineral Resources and Ore Reserves are reported on an æinclusive ofÆ basis.

Jan 1, 2003

By F Pothitos, S Hewson

The geological and geotechnical conditions at the Cadia Hill Open Pit are very complex. This complexity coupled with high mining rates has required significant technical input into the design and optimisations of the pit slopes, accesses, cutbacks and scheduling. A multi-discipline team of NML engineers, geologists and external consultants has been conducting comprehensive geological and geotechnical programs in order to achieve an optimum design of the pit slopes. Extensive data collection, analysis and interpretation has led to the formation of working geotechnical models of large structures, rock masses, and back-analysed slope performance charts. The current Cadia Pit Optimisation Project focuses on the risk-and-return principle for pit design and on the integration of geotechnical, hydrogeological, mining engineering and scheduling. The risk management for pit design has also been incorporated into the short term and long-term operation of the pit mining to ensure safety and production.

Jan 1, 2003

Mining companies around the world are seeking methods to coordinate operations between the mine and the concentrator to achieve an overall improvement in enterprise performance. In several instances very significant increases in productivity (more than 20 per cent) and profitability (more than $US 10M per annum) have resulted from such efforts. The key to realising these large benefits has for the most part arisen from improved communication between mining operations and plant operations personnel and the judicious use of new tools to evaluate alternatives for improvement and to minimise the risk of implementation. This paper presents a systematic approach to mine-to-mill optimisation . The importance of systemic thinking and systems optimisation methodologies is emphasised. New tools for evaluating operational performance are discussed. Recently reported benefits are summarised. Finally current research is discussed and projections for the future are given.

Jan 1, 2000

By Simpson D, Skopakow J

This paper is one of the series of papers relating to the Melbourne Underground Rail Loop and specifically describes the structural and architectural design of Museum Station. Structural arrangement, loads and design methods of the major temporary and permanent works are briefly described for the main station and entrance works. Planning of the station concourse area, booking halls and entrances are described together with the selection of finishes for all above and below ground areas.

Jan 1, 1981

By Muir D

A review of the various methods of degrad- ing cyanide either from gold processing liquors or electroplating baths is presented with some discussion on their relative merits or problems. Whilst alkaline chlorination is common practice in many U.S. and Canadian plants it poses particular problems for certain plants. Alter- native methods include electrolysis, hydrolysis and air oxidation with activated carbon as catalyst which are also integral steps in the carbon-in-pulp process. A basic study of the degradation of cyanide ion has been carried out therefore to determine the effect of temperature, oxygen and carbon. It is shown that carbon is an excellent catalyst for degradation by air and likely to lead to higher losses of cyanide in a C.I.L. circuit. Degradation by hydrolysis is important at high temperatures and high pH such as employed in the Pressure Zadra or Anglo elution processes. Carbon catalysed degradation of cyanide by oxygen in effluent streams may be an environmentally acceptable alternative to conventional chlorine degradation.

Jan 1, 1987

Silver-lead mineralization at Indooroopilly, Queensland, extends upwards from Upper Triassic rhyolite which intrudes phyllite-containing Palaeozoic mineralization.Sulphides and magma were emplaced in a special structural site which underwent dilational fracturing while surrounding rocks were block-faulted and compressed. This site lies at tbe intersection of dykes, faults, and a lineament adjacent to a Middle Triassic granitic stock.Structural controls at Indooroopilly are attributed to the effects of piston faulting. Exploration for similarly controlled deposits should be directed towards structural intersections near stocks or batholiths which have intruded mineralized belts. Priority should be given to structural intersections which were sites of block-faulting and igneous activity under compressional tectonic conditions.Favourable sites lacking surface mineralization may contain ore at depth as piston faulting produces 'blind' ore deposits.

Jan 1, 1976

By B Wiggins, M Russell

Off-gas handling systems are a critical component of modern metallurgical furnaces and typically represent as much as 50 per cent of the total installed smelter capital cost. Inadequate off-gas system performance, due to insufficient exhaust flow or excess maintenance downtime, can present a serious process bottleneck and limit smelter production rate. Therefore, it is essential that the relevant performance issues are fully understood and considered in the design of these systems, particularly when combustibles produced within the furnace must be combusted or handled in the off-gas system. This paper examines the requirements, design issues, and conceptual design process for state-of-the-art postcombustion off-gas systems. The relevant design considerations of safety, environment, energy consumption, and maintenance are presented, and the relative importance of these key issues are compared and discussed. The benefits of using computational fluid dynamic (CFD) modeling in the design process at the conceptual design stage are also demonstrated. Finally, the design basis and performance of a recent Hatch-engineered system currently in operation is evaluated.

Jan 1, 2002

By Henderson J

Iron ore samples selected from the Deepdale, Iron Prince and Mt. Newman ore bodies have been pelletised on a pilot scale plant and subsequently reduced under laboratory conditions by hydrogen or carbon monoxide. Pellets approximately 1 cm in diameter have been reduced by hydrogen over the temperature range 5000- 900¦C and the results examined by thermogravimetric, microscopic, electron probe and x-ray techniques. After an initial time delay it was found that up to 95% reduction the rate of reduction could be described by a transport con- trolled porous model, in which the effective diffusivities of hydrogen in theòpr¦duct layer and the reaction zone are filar. Independent measurements of effective diffusivity supported the values obtained from the reduction data. ve 95% reduction the rate decreased markedly due to the formation_of retained wustite or fayalite. Comparison with reduction by carbon monoxide over the temperature range 7500 - 900¦C showed that the rate eduction by carbon monoxide was approximately five times slower than the rate by hydrogen. The rate of reduction was found to be a function of the properties of the pellets, which may account for the ely conflicting results that have been obtained in previous investigation on porous pellets.

Jan 1, 1970