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By Mortensen JK, Lang JR

The Canadian Cordillera contains numerous classic porphyry deposits and several unusual subtypes, including the alkaline suite of porphyry Cu-Au deposits and the Tombstone magmatic suite and associated Au¦W deposits. The alkaline suite formed in collisional settings in island arcs whereas the Tombstone suite was emplaced in an active fold and thrust belt in a continental arc. In addtion to different regional settings, these suites differ in the type of underlying basement, metallogeny, and the styles of mineralization. Both magmatic suites were emplaced over short intervals, probably in response to specific tectonic events. In the case of the alkaline suite, the tectonic event promoted magmatic processes suitable for the formation of porphyry Cu-Au deposits. The tectonic environment is less well constrained for the Tombstone suite, but the result was the formation of distinctive porphyry and intrusion-related Au¦W deposits.

Jan 1, 1995

Chief Geologist, Groundwater and Engineering Geology Branch South Australian Department of Mines and Energy The six papers submitted for consideration during this session include two dealing with techniques for measing rock mass behaviour, including permeability, in boreholes, one describing the use of surface geophysical methods to delineate pollution plumes in groundwater together with analytical modelling of the plume, and one presenting a biological tracer technique applied to the determination of the origin of water entering underground mine workings. A paper describing dewatering at a base metal mine in Queensland includes an account of the investigation techniques employed to establish a conceptual model as a basis for the evaluation of various dewatering strategies. Of considerable interest is the use of a field gravity survey to delineate a zone of highly weathered rock which forms the major aquifer at the site.

Jan 1, 1988

By Stevens LG, Mok JK

With the long lead time requirement for engineering and construction of mineral pro- cessing facilities and the costly financing arrangements necessary, effective project management is essential to the successful and timely start up of these major production units. An added complexity is the frequently remote location of such projects and the demands this imposes on efficient project staffing, scheduling, logistics and cost control. Parsons recent experience with major projects such as Greenvale in Queensland and La Caridad in the desert of Northern Mexico and at remote locations like Sar Cheshmeh in Iran are described. The applications being developed for improving project controls through the use of computer techniques such as MSCS-COPES, and readily accessible and versatile transportation means are reviewed.

Jan 1, 1981

By Brasnett TC

A wide variety of problems are encountered on a day to day operating basis in the Isa Mine Concentrators. These vary from complex textural problems in the lead-zinc concentrator and their subsequent effect on grinding and flotation to scheduling of converter slag treatment in a chalcopyrite concentrator. With the advent of process control, metallurgists need to specialise and keep up to date with technology improvements. This paper will attempt to describe the significant problems'faced by a Metallurgist û Control.

Jan 1, 1978

By Hyde L. J

Blasting is one of the available technologies to be employed in underground excavation systems. In many instances it can be the only technology which is suitable. The recent moves towards more mechanised working systems is resulting in a reduced awareness of new blasting practices and technologies on the part of many excavation engineers. Recent developments in blasting systems can be utilised to significantly improve operating efficiency, reduce total cycle times, better comply with regional environmental constraints and reduce the total cost of underground excavation. Blasting is and will remain, a very adaptable and exciting alternative which is far from boring.

Jan 1, 1987

Bulk mining and handling technologies have been affected in two ways by the soaring costs of oil products in recent years. Firstly, the substition of oil by coal, oil sands and oil shale demands the development of high-capacity mining and handling equipment, and secondly the rising fuel costs favour a trend away from cost-intensive heavy truck transport. To cope with the growing volumes of material in mining and handling, larger equip- ment units have to be designed. This tendency becomes apparent from the examples of the Hambach open pit mine in Germany, and the Port Kembla handling plant in Australia. A combination of the flexibility of heavy truck transport and the cost advantages of belt conveyors is achieved by the system of semi-mobile crushing installations described in this paper.

Jan 1, 1981

Epithermal deposits have been defined as the lower temperature end of a spectrum of hydrothermal mineral deposits and are inferred to have formed near the EarthÆs surface. The preservation of an epithermal gold deposit in an Archaean craton is rather problematic, especially when such deposits form clusters or groups as reported for the Pilbara and Yilgarn cratons. For two of the better studied examples of epithermal gold deposits in these cratons, Becher and Wiluna, the evidence that they formed near the Earth surface is non-diagnostic, and the epithermal origin appears uncertain. Despite the simplicity of the original definition, there have been numerous errors in classifying epithermal gold deposits. It is suggested that these errors are primarily due to poor criteria defining the group as there is limited evidence of poor observational science being the cause. The criteria being used to recognise epithermal gold deposits include tectonic setting, ore element suite and quartz vein textures. None of these are diagnostic of epithermal deposits and their link back to the original low pressure-temperature definition of the class is tenuous. There has been definition creep over time as new observations on potential epithermal gold deposits become accommodated within a flexible definition. There is some urgency establishing and then using criteria to reliably identify epithermal deposits. Distinction of epithermal gold from weathered gold deposits is an important step. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By Forssberg E

This paper presents the experimental results on the effects of slurry Theology on ultra-fine grinding by a stirred ball mill. The amount of dispersant, slurry density and the particle size were selected as the parameters. The viscosity of dolomite-water slurry was measured by rotational viscometers. It was found that by adding enough dispersant, the effect of particle size from 1 to 10 pm on the slurry theology could be eliminated, but a strong effect of slurry density (tested for a range of 65 to 75 wt per cent) remained. The use of dispersant transformed the slurry from Bingham plastic flow to dilatant flow, which reduced the yield stress to zero, but increased the viscosity at higher shear rates. During the milling process, the viscosity was stable. The yield stress, however, increased suddenly from zero after a certain milling time. The mill operation stopped at the point where the yield stress increased due to poor slurry fluidity. The milling efficiency was found to be higher at a lower amount of dispersant addition or a lower slurry density within the experimental limits.

Jan 1, 1993

Blasting effectiveness must be gauged by total production costs. ANFO charges made up in polythene "sausages" are not as profitable as is indicated by the price of ANFO. All-slurry charges are warranted only where blastholes cannot be dewatered effectively, or where drilling costs are very high. An increase in blasthole diameter leads to coarser fragmentation. This effect is most pronounced in tough and massive or blocky strata, or in ground which consists of unfissured boulders in a softer matrix. When ANFO and some slurry-type charges of small diameter are used in plastic-acting ground, charges may fail to detonate through precompression by charges fired on an earlier delay. The optimum blasthole length is rarely less than four times the burden distance. For best results, blastholes should be inclined to the vertical and parallel to the face. Nominal burdens and spacings are often altered radically by the initiation sequence. For best fragmentation, all blastholes must have good effective faces, and should be effectively stagg- ered with an actual spacing:burden ratio in the approximate range 2.0-5.0.

Jan 1, 1975

Structural assemblages of veins, shear zones, and wallrock alteration zones arising from fault-valve action on steep reverse fault systems are reviewed using observations from mesothermal gold-quartz lodes in the Archean Yellowknife, Abitibi, and Yilgarn greenstone belts of Canada and Western Australia, the Cretaceous Mother Lode system in the Foothills Metamorphic Belt of the western Sierra Nevada, California and the Victorian goldfield hosted in a folded quartz-turbidite succession of Paleozoic age in Australia. Despite differences in the host rock assemblages, the deposits have many structural characteristics in common. These form a useful exploration guide when re-evaluating comparable, but poorly described gold-quartz vein systems such as those in the Reefton area of New Zealand.

Jan 1, 1992

Western Mining Corporation (WMC), managers of the Windarra Nickel Project, installed a raise-bored haulage shaft and underground crushing system at the Mt Windarra Nickel Mine in 1982. The system is the second of its type installed by WMC, the first being at the Otter Juan Mine in Kambalda in 1976/77. Both haulage systems became necessary as a result of the increasing production limitations, and escalating costs of a deep decline mine.The Windarra haulage system required a single 3 m diameter vertical raise drill hole, 470 m deep and equipped for skip haulage. Two five tonne skips, in balance, hoist crushed ore and mullock to the surface, at a design rate of 200 tonne/hr, effectively reducing truck haulage leads by up to 50 per cent. The system is now fully operational and will enable the mine to achieve its maximum production rate.The raise-bored shaft system has been shown to be cost effective and would be used again in circumstances where raise drilling is applicable.

Jan 1, 1984

This paper describes a steam outburst in a metal mine which occurred in December 1992 in Japan, resulting in two fatalities. The outburst occurred just after blasting in a heading face 600 m below surface (SL-50 m), 1664 m from a mouth of the mine. The scale of the outburst was large and the fragments of the outburst spread up to 34 m from the face, the total volume of the outburst was estimated to be 206 m3. The outburst materials were mostly clay originated from the typical surrounding rock of sulfide ore and basalt. The shape of the larger outburst fragments were slabs with a thickness of 10 to 20 cm. The victims were found in a main ventilation air shaft, 175 m and 380 m from the face, respectively. The mine mainly produces copper, lead and zinc. The face was ventilated by a 560 mm diameter duct with a fan and the strata temperature of the rock was estimated to be in the range of 120 to 140¦C. There is a famous hot spring near the mine. A thorough investigation into the unprecedented accident was made including an on-site inspection and investigation of rock characteristics in laboratories.

Jan 1, 2005

By J P. R de Villiers

The Vanderbijl Park sinter plant in South Africa was investigated to determine the reason for the production of very fine sinter not acceptable as feedstock for the blast furnace. A procedure was designed to generate representative samples and to prepare the samples for chemical and mineralogical analyses. Results from a mineral analyser showed that the samples are extremely heterogeneous and therefore the sampling and sample preparation methods had to be tested in order to produce representative samples. The high production capacity at the sinter plant could also give rise to sampling errors. The method designed involved sampling of the conveyor belt at the sinter plant every four hours for the duration of three days. The samples were then milled and split into smaller sections appropriate for analysis. X-Ray diffraction (XRD) and X-Ray fluorescence (XRF) analyses were conducted on the samples. The results showed a standard deviation of less then one per cent, which indicates that the samples were representative and that the method used was therefore adequate. Systematic differences in the phase proportions between normal and fine sinter samples were detected, with the fine sinter containing more haematite than the normal sinter. The sampling method employed gives added confidence that the differences are real.

Jan 1, 2008

Full aerodynamic design development of the proposed fans for the enlarged primary ventilation system at Mount Isa Mines Limited was initiated before tender specifications were prepared. Theoretical and analytical design studies were made of many possibilities to determine the optimum proposal. Major considerations were efficiency, simplicity, standardization, and mechanical feasibility. Model testing and experimental work covered blading design, inlet shape, diffuser and tail fairing dimensions, instrumentation requirements, ancl noise studies.Theoretical and predicted performance estimates were prepared for the three 20 ft diameter vertically mounted axial flow fans.

Jan 1, 1967

By McNicol J. H

Using a small scale laboratory pilot plant a series of tests have been conducted with the aim of investigating the influence of the zinc/acid ratio on the efficiency of zinc electrodeposition from an acidic sulphate solution. The results have shown that current efficiency is increased as the zinc/acid ratio is increased with no evidence of an optimum zinc/acid ratio. However the choice of a zinc/acid ratio for full scale operations must be a compromise between other parameters, spent electrolyte acidity and power efficiency, which also impact upon plant performance. The effect of various impurities has also been monitored and antimony, nickel and tin have been shown to be deliterious to current efficiency.

Jan 1, 1989

THE following paper is a description of the plant and operations of the above company in their recovery and treatment of the quartz tailings deposited as final residues by the various mining companies. at Waihi, Karangahake, and Waitekauri into theOhinemuri River. During the past few years the silting of the Ohinemuri River has increased to such an extent as to cause considerable interest and discussion, and has lately been the subject of a most extensive inquiry by a Royal Commission, to consider the best means of dealing with what is generally spoken of as a public nuisance.Ever since the commencement of mining in this district, which was opened as a goldfield in 1875, the various mines operating have been discharging their tailings into this river, it having been proclaimed a sludge channel in 1895. Up to the year 1900 the quantity of quartz crushed was not large, probably not exceeding 500,000 tons; but since that date the annual tonnages discharged have increased enormously, and at the present time would total from 550,000 to 600,000 tons per year. Records show that up to the end of 1910 at least 5,000,000 tons have been crushed, for an actual yield of bullion considerably exceeding £10,000,000 in value, and all the valuable tailings from...

Jan 1, 1911

The latent conditions clause in various general conditions of contract have traditionally proved to be a source of significant disputes in tunnelling contracts, even when extensive geotechnical investigations have been carried out at the tunnel site and a report of these investigations provided with the tender documents, informing the contractor of the nature and extent of subsurface conditions likely to be met with during execution of the works. This paper discusses the contractual aspects of the new latent conditions clause in the recent Australian Standard AS 2124-1986, General Conditions of Contract, in relation to tunnelling contracts. A comparison of this new clause is made with other latent conditions clauses in general conditions of contract in use in Australia and other commonwealth countries. It is seen that the new latent conditions clause in the recent Australian Standard 2124-1986 has, by providing for a reasonable apportionment of risks, attempted to minimize contractual disputes relating to latent conditions in tunnelling contracts and to provide a satisfactory basis for quick and efficient settlement of such disputes should they arise during execution of these contracts.

Jan 1, 1987

The capabilities of the three 61R and one 81R Robbins Raiseborers currently in use at Mount Isa are defined. Their applications in the development of ventilation and hoisting shafts, orepasses, escape routes, fill passes etc. are described and possible future uses of these and newer raiseborers at Mount Isa are examined. Problems associated with the use of raiseborers, together with ways of overcoming them are discussed. The impact of raiseborers on the mining operation is assessed in terms of new approaches to design and development, safety, cost and manpower efficiencies.

Jan 1, 1974

By J Player, K Braddon

High productivity mining is the key to the financial success and stability of modern mines. This can be achieved through the use of new technologies, the development of innovative work practices and optimisation of the mining method to suit the mining environment. Big Bell Mine is a 1.7 Mtpa longitudinal sublevel caving operation at a head grade of 3.14 g/t. Annual production is 170 000 ounces of gold. The selection and implementation of bulk emulsion explosives was seen as the logical progression from blow loaded ANFO for the high tonnage rate required from the longitudinal sublevel cave. Prior to the implementation of bulk emulsions an investigation was required to examine the technical and financial benefits available with the introduction of bulk emulsion. This paper examines the review process and the successful implementation of bulk emulsion explosives at Big Bell.

Jan 1, 1999

By Stewart C. A

The Northparkes copper-gold project is being developed in Central Western New South Wales approximately 30 km NNW of the town of Parkes and approximately 350 km west of Newcastle. The project is a joint venture between North Limited (80 per cent) and the Sumitomo Group (20 per cent). North is the manager. The basis of the project is three copper-gold orebodies, the northern two of which are being mined by conventional open cut methods with the third and largest orebody at the southern end of the lease to be mined by block caving. A fourth mineralised body has been identified in the centre of the lease. While further evaluation of this deposit is required it would appear to be amenable to block caving. Oxide caps of gold ore and copper-gold ore over-lie the two northern orebodies. Development commenced with the construction of a carbon-in-pulp (CIP) plant to treat the oxide gold ore. Construction of a flotation plant to treat oxide copper-gold ore and sulphide copper-gold ore is underway. When full-scale operation is achieved late in 1996 the plant will treat 5.0 million tonnes of ore per year of which 1.1 million tonnes will be open cut ore and 3.9 million tonnes will be block cave ore. In terms of annual ore tonnage the underground mine will be the largest metalliferous mine in New South Wales and the second largest in Australia.

Jan 1, 1995