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By Gemuts I, Hudson D. R

Massive sulphide mineralisation at the Miriam prospect, near Coolgardie, Western Australia, is fracture-controlled and associated with disseminated sulphides near the basal contact of an ultramafic lens. The lens is peridotitic in composition with a pyroxenitic zone at its base, and lies within a sequence of altered high-Mg basalts and pillowed tholeiitic basalts. Recrystallisation of the ultramafic rock has resulted in the development of secondary olivine. The average composition of the sulphide fraction of massive ore is Cu = 4.4%, Co = 0.3%, Ni = 23.0%, Fe = 31.8%, S = 40.6%, consisting of the supergene assemblage violarite-pyrite to a depth of 210 m.

Jan 1, 1973

In Australia 'there are hidden deposits of gold, copper, tin, lead and zinc which can be found by drilling at reasonable expense in view of the imp9rtance of the objectives. Exploration of the prospects in mind would mean about a million feet of drilling. The purpose of this paper is to outline, in a technical way, some of the geological thinking that has been given to this matter. To do this, it is necessary to unify the wider ranging thoughts into some sort of coherent perspective and also into some sort of logical sequence. This will be done by treating first the geological subject material which is in fact, at the foundation of the exploratory scheme. With this base, the argument will be continued through a sequence of prospect thinking and brought to a conclusion in regard to the practical employment of geology in the drilling planning. In this knitting together of ideas, the discussion will be given substance by welding into the argument the reasoning that has been applied to the Cobar prospect. The New Occidental Gold-Mines are operating three mines at Cobar, and the writer is indebted to the Company for allowing the reference to be made. It is intended, as opportunity permits, to furnish further examples in later publications.FOUNDATION OF EXPLORATIONThe deposits under consideration are derived from igneous rocks, chiefly granite or porphyry. In and following the emplacement of the intrusives, the rocks have been...

Jan 1, 1946

Most of the gold reef mined today in South Africa is approximately 1 m in width with slopes about 30 m long. To prevent production interruptions it is essential that the stopes should not be blasted in sections. The shortage of experienced labour and arduous working conditions at the face dictate the need for simple blasting techniques.Hence, a pyrotechnic blasting system of sequential firing is in use at present, although research work to improve this technique is in progress.

Jan 1, 1985

By Russo S

Metals Refining Operations Pty Ltd (MRO) began refining gold in PNG in 1991 and has undergone continuing growth since then in servicing an everchanging and growing market. MRO's ownership combines PNG Government interests and Golden West Refining Corporation Limited as operator.Features include a very diverse range of suppliers, a full range of technical methods and challenges and the financing and marketing responses unique to a developing country. These areas are examined and documented with special emphasis upon the service needs for the gold industry and future trends and challenges are discussed.

Jan 1, 1997

The ore reserves of the Frieda porphyry copper prospect in Papua New Guinea have been estimated using kriging and an alternative method. Only very erratic variograms could be obtained from the raw data and thus it can be expected that kriging variances will be unrel- iable. The frequency distributions of the two sets of estimates show expected differences and the resulting mineable reserves show similar expected differences. More drilling and the use of disjunctive kriging are needed to produce reliable estim- Ates.

Jan 1, 1979

By Millen M. J, Rainey S, Sowerby B. D

The control of size reduction in grinding machines and circuits may be enhanced by a continuous and accurate measurement of the particle size of solids in appropriate process streams. This paper presents a brief review of commercial particle s

Jan 1, 1997

By Mullens P

Recent advances in technology have allowed many of the problems of directional control of long diamond drill holes to be overcome. Three case histories are presented, from Cobar, Hilton North and Mount Isa Mine, in which careful hole design and the use of wedges and down-the-hole motors have allowed tight directional control of drilling. Substantial savings in time and cost were achieved in all three cases.

Jan 1, 1990

The paper presents the results of laboratory blasting and grinding experiments on a low-grade iron ore, investigating how blasting will influence the subsequent crushing and grinding operations. Increased blasting energy will lead to a reducti

Jan 1, 1998

The highland region of Papua-New Guinea is relatively rugged terrain where stream gradients are steep. In areas where porphyry copper deposits outcrop the streams commonly expose primary sulphide mineralization in unoxidized rocks. Stream sediment geochemistry combined with float examination and broad geological mapping proved to be an effective tool for detection of outcropping bodies of mineralization. After discovery, detailed stream sediment sampling, soil sampling and rock chip sampling, together with detailed geological mapping proved adequate to delineate drilling targets. Reconnaissance stream sediment sample density was dictated by geology and access and a density of one sample per 25 Km2, or less, was desirable to ensure a high degree of confidence in the programme. Research indicated that the base metals occur in sulphide form in stream sediment and that the -80 mesh size fraction gave the most reliable results. The evaluation of results from any one area relied on the interpretation of the local geology. Basic histogram methods for determining background and threshold values for metals in stream sediments were

Jan 1, 1973

By Kapoor M. L

Emf measurements on SE galvanic cell: SS; Ni-NiO I solid electrolyte/ZrO2 + CaO I [Pb + Bi]liq alloy; (PbO); SS were made in the temperature range 913-1034 K to determine the thermodynamic properties of oxygen dissolution in liquid lead. Bismuth alloys with bismuth in the dilute concentration range of 0 to 3.08 mass per cent and oxygen in the alloy varied by equilibrating the metallic system with a suitable (PbO) slag. Wagner's interaction parameter approach was used to calculate the ternary interaction parameter, eBiO at temperatures of 913, 953 and 993 and 1034 K and to observe the temperature dependence eBiO = 19 200/T - 17.454. Quasichemical fonnulation was employed to yield lnf BiO and reveal the effect of bismuth on oxygen in lead. The results obtained are discussed on the basis of theoretical models and the value of Wagner's energy parameter 'h' estimated to predict the results in a Pb-Bi-O system.

Jan 1, 1995

By Kelly GD

Prior to 1986, users of satellite based remotely sensed data were almost exclusively reliant on the United States Landsat series of satellites to monitor our Earth's resources. This situation changed when France, Belgium and Sweden launched SPOT-1 in 1986. The year of 1988 saw the Japanese also enter into the earth resource satellite business. The Japanese launched an earth resource monitoring satellite with an emphasis on marine resources, hence the name MOS-1 (Marine Observation Satellite). Many more remote sensing instruments are planned for launch by these nations and others in the next 10 years.

Jan 1, 1990

By R Turner, P Hatherly, T Medhurst

Borehole geophysical logging data are routinely acquired during exploration of coal deposits in Australia. These data are commonly used qualitatively to identify and correlate coal seams and geotechnically significant interburden rock units. Some quantitative analysis, such as using sonic logs for rock strength estimation is becoming increasingly widespread. This paper discusses results from a project aimed at expanding the quantitative approach to more detailed mineralogical and lithological analysis, which leads to improved geotechnical characterisation for mine planning and mining hazard reduction. A standard suite of wireline logs measuring density, natural gamma, sonic and neutron were analysed from three coal mines in the Bowen Basin. Thirty-nine samples from cored sections of the boreholes were analysed by X-ray diffraction, spectral gamma counts and hyperspectral scanning. Using a standard petrophysical approach to calculating porosity, shale and matrix components from a combination of density, natural gamma and neutron logs, a good correlation with observed mineralogy was demonstrated. However, unusual mineralogies such as heavy minerals or low-potassium clays may distort this analysis. Simultaneous evaluation of all available geophysical logs by modern data mining methods was able to show how these ambiguities may be solved.

Jan 1, 2006

With the recent wider introduction of friction hoists of the Koepe type. for winding from depths of more than 3000 feet it has been found that failure by fatigue is the most common form of rope deterioration. Large numbers of wire breaks occur near the centre of the rope cross-section and it is difficult to detect these with certainty using the preferred d.c. magnetic test. For best results with conventional search coils their dimen- sions should be related to the typical wire break field pattern surrounding the longitudionally magnetised rope. The field of a broken wire was experimentally determined, using a Polish type MD6 Defectograph wire rope testing magnet and a short prepared length of rope with a movable simulated broken wire. The external field distortion perpendicular to the rope was measured by means of a gaussmeter and Hall probe. The advantages of this method are that terrestial magnetism and inherent rope "noise" have no effect on the results.

Jan 1, 1971

By Cripps-Clark CJ, Deague TK

In order to study conditions under which SiO(g) may be formed in a blast furnace, equilibrium phase diagrams were constructed for the combustion of high and low ash cokes with oxygen-enriched blast and oil injection under conditions of high and low raceway pressures. Free energy minimisation techniques were used to calculate the composition of gaseous and condensed phases. Where coke ash is assumed, for simplicity, to comprise Si02 only, the coke can be comple- tely gasified, mainly to SiO and CO, under restricted conditions of coke to blast ratio and at temperatures greater than 1600 - 1650¦C, depending on system pressure. The formation of SiO(g) is partially suppressed by the introduction of alumina into the ash, because of the formation of solid and liquid alumino- silicate compounds. The minimum temperature for complete silicon gasification is raised to about 1700¦C. The results of the equilibrium calcula- tions are related-to actual raceway conditions. It is proposed that virtually all silicon in the coke ash is gasified such that, on condensation, it affects hot metal chemistry and slag properties and secondly, that the effects will be greater with higher ash cokes.

Jan 1, 1980

By Ulvelin K, Antila K

Large scale cut and fill mining in narrow silver-lead-zinc orebodies began at Mount Isa in 1964. Initially each orebody was one stope and access was via raises from the level above. Upholing was the principal mining method, although flatbacking was employed where ground conditions were more difficult. Developments since have included access via footwall inclines and connection of all stopes with major crosscuts. Flatbacking is the principal method. The most recent cut and fill operation is now fully mechanised using drilling jumbos, rockbolting jumbos and load-haul-dump units. Improved ground support and drilling and blasting practices have enhanced safety, recovery and productivity in all cut and fill operations.

Jan 1, 1988

The resources industry is unique in that the finite nature of resource deposits requires a participant to be constantly locating and developing new ones to replace those that are depleted. An effective growth strategy that enables new project developments to be brought on line in time and within budget is therefore of fundamental importance to any mineral resources company. This paper seeks to identify the role of the development project in the company's overall growth strategy and the key performance criteria that a development project must achieve in order to allow a company to meet its growth objectives.

Jan 1, 1997

By Bennet A. G

As part of the construction of the Melbourne Underground Rail Loop it was necessary to construct two 7 metre diameter tunnels, each 100 metres in length, by shield driven excavation through an alluvial valley at Elizabeth Street. The tunnels had a primary support of bolted precast reinforced concrete liner blocks and were excavated with the aid of compressed air. The work was undertaken by the Tunnelling Group of the Melbourne and Metropolitan Board of Works as nominated sub-contractor to John Holland (Constructions) Pty. Ltd. The paper describes some of the problems associated with the construction of the above tunnels and the methods used to overcome them. In particular

Jan 1, 1981

By Guo H

The importance of using disc cutters for rock excavation is reflected by their wide application in hard rock cutting machines such as tunnel boring machines and raise borers. The forces involved in the cutting process are those due mainly to thrust and rolling forces and are greater than that required by cutting picks. An interesting feature of cutting with discs is the formation of surface crushing, surface and sub-surface chipping and primary crack formation. Experimental, as well as analytical, work has been carried out to determine the optimum spacing between the disc cutters to control primary crack orientation. Wedge bit indenters were used to simulate disc cutters. The paper concludes by proposing a new approach to rock excavation by hybrid cutting based on controlling the primary crack Orientation.

Jan 1, 1992

Incompetent ore and country rock have caused stability problems in longhole open stopes. Fully grouted pre-placed cablebolts have reduced these by preventing ground relax- ation and joint dilation to maintain a self supporting rock structure. Larger atope spans can now be opened with the same or smaller pillar. Mining methods are expected to become less dependent on original ground conditions. Effect of spacing, orientation and stress distribution along the cablebolt is not fully understood at this stage and requires more Observation.

Jan 1, 1977

By Orid A

A fast, non-contact technique for measuring sizes of rock fragments on a conveyor belt is presented. An image processing technique called active stereopsis is used which makes use of a light stripe projected on to the surface of the fragments on the conveyor belt. A CCD TV camera is used to capture the shape of the distorted light stripe. the video image of this shape is then processed by a computer program so that the 3D profile of the surface can be obtained by triangulation. The sizes of the rock fragments are then calculated from this profile. The speed of the technique is improved by calibrating the light stripe system before measurement begins so that the profile of the fragment surface can then be measured using simple geometry. The technique is fast and highly parallel so that it is able to operate in real time.

Jan 1, 1990