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The recommissioning of the plant at Mary Kathleen involved several distinct phases. The previous plant process was modified significantly, the plant capacity was increased by the addition of new equipment and the exist- ing equipment was in most cases overhauled. This equipment was either reused in its original duty or relocated. Maintenance requirements after the plant was cmommissioned were high because of the amount of modified equipment and also because some old items of equipment were deliberately not overhauled during recommissioning. The equipment that was overhauled has operated reliably. However some new equipment has not been as satisfactory.

Jan 1, 1978

By Struthers M. A

The basement contact zone, a major fault structure underlying the copper orebodies at Mount Isa, has a significant influence on orebody extraction. The zone is comprised of a variety of weak, barren lithologies which often create very difficult mining conditions, contribute to stope dilution, and have an adverse effect on concentrator recoveries.The geological characteristics of the contact zone are described, and the importance of timely, accurate geological information emphasized.A variety of mine design strategies have been employed to reduce the impact of the contact zone on orebody extraction. Some of these are discussed, together with current trends in the southern areas where orebody geometry and hence mining methods change markedly.Recent developments in ground support techniques, such as cable dowel reinforcement, have significantly improved ground conditions in the contact zone. An example of the methods employed to improve knowledge of ground behaviour is presented. The trend towards increasing automation and larger equipment requires larger excavations; consequently ground support practices and knowledge of ground behaviour must continue to advance. Rock mechanics investigations will remain an essential part of the mine design process.

Jan 1, 1990

China has been producing gold for more than 4000 years with gold production increasing substantially since the 1980s, from about 25 tonnes in 1980 to some 160 tonnes in 1998. More than 80 per cent of the gold production is from East China. However, complete information on eastern China gold has been rarely reported internationally. This is a general overview on the tectonics and metallogeny of gold deposits in East China. The geology of these gold deposits is compiled mainly from data and information reported in China, and is also based on the authorÆs work in China from 1974 to 1986 and a recent visit to China.

Jan 1, 1999

By McCarthy P. L

With production at Olympic Dam scheduled to commence in June 1988, it has been necessary to install a complete underground ore handling system capable of removing two million tonnes of material annually from the mine. The system comprises mucking from stope drawpoints, truck haulage to underground storage, primary crushing, conveying and hoisting. On the surface, material is conveyed to stockpiles at the Metallurgical Plant. Mining of the numerous special excavations within the system was incorporated into the mine's ongoing development program prior to the underground construction phase. Utilisation of a decline from the surface enabled versatile construction equipment to operate at the underground sites as well as simplifying the transportation and delivery of construction Materials.

Jan 1, 1988

By McKew M, OÆRegan

Rapid access longwall mining' or 'longwail punch mining' is a proposed extraction method whereby longwall gate roads are driven into a seam directly from an opencut highwall. The longwall panel thus formed is retreated back to within 40 m of the highwall providing an extremely simple, reliable and therefore highly productive longwall mining system. The concept is of particular benefit for the recovery of isolated pockets of coal (adjacent to a highwall) not easily accessible from a conventional underground mine. As panel gate roads are driven directly from the open strip, minimal delays are incurred between the end of open cut and start of underground production, allowing the method to bridge the gap between open cut mining and a total underground commitment. The study was specific to the Bowen Basin, and given the likely conditions, no significant operational or geotechnical hinderances to the concept could be identified. It was therefore concluded that longwall punch mining would not expose the operator to any additional risks above that normally associated with the introduction of longwall mining. Thus, longwall punch mining is an attractive option, both operationally and financially, for open cut mines reaching their maximum economic Death.

Jan 1, 1988

By Scott A

The object of most blasting operations is to destroy the insitu structure of the rock mass so that mechanical equipment can efficiently excavate the rock fragments. In achieving this objective the blasting engineer is also concerned with minimising damage to the adjacent rock which forms the mine structure relied upon to provide support. Damage to this "structural" rock is undesirable but usually occurs as a result of two distinct processes: ò readjustment of stresses around the excavation as a result of the mining process itself ò impact of vibration and high pressure gases from blasting operations. Gross damage to mine structures from either cause is observed as visible alteration to the appearance of the rock structure in the form of cracking, slabbing, back or over break and visible displacement. Recent work at the Julius Kruttschnitt Mineral Research Centre (JKMRC) has shown that significant reduction in the strength of a rock mass can take place well before the onset of these obvious signs of damage. It has been demonstrated that the effect of blast damage on the behaviour of the rock mass can be many times more prominent than the effect of stress redistribution. This offers the blast design engineer the opportunity to significantly reduce blast induced damage to rock structure by modifying blasting practices. This paper introduces the current JKMRC postgraduate research projects investigating the evaluation and control of blast damage.

Jan 1, 1990

By D M. Weedon

This paper introduces a novel roll crusher design, which incorporates non-cylindrical crushing rolls. The use of non-cylindrical rolls enables the crusher to achieve a greater reduction ratio than is possible with conventional roll crushers. Referred to as the NCRC (non-cylindrical roll crusher), the new crusher incorporates two rolls comprised of an alternating arrangement of plane and convex or concave surfaces. The two rolls are complementary and arranged so that when they rotate the convex and concave surfaces of each roll are substantially opposed. With the rolls rotating in opposite directions at the same speed, this arrangement produces a gap between the rolls that remains approximately constant. Discontinuities on the roll surfaces provide improved angles of nip, which increase the probability of larger particles being drawn into the crusher. Initial tests on a scale prototype of the NCRC have indicated that reduction ratios exceeding 10:1 are achievable.

Jan 1, 2000

By Napier-Munn TJ

The Whiten model of crushers is currently being refined and extended at the JKMRC, with particular reference to cone crushers. This paper describes the model as a predictor of crusher power draw, discusses the application of the model, and considers the relationship between power draw and crusher performance.

Jan 1, 1988

By Zhang S

A probabilistic approach is proposed for updating open pit slope sta- bility based on successful performance. The suggested approach is developed within the framework of Bayesian probability theory. In seeking solutions to geomechanics problems consideration must be given to inher- ent variability of shear strength parameters and to the errors in the esti- mation of these parameters. The latter can be significant and may lead to consistent overestimation or underestimation of the values derived from site investigation and testing. Conventional deterministic methods of slope stability analysis do not allow systematic modelling of uncertainties in applied loads or in shear strength parameters. Within a probabilistic framework indicators of stability may be calculated, e.g., the reliability index and the probability of failure. Based on observation of slope per- formance at any given stage of a project, the mean or the standard devi- ation (or both) of a shear strength parameter may be updated. Consequently the indicators of stability can also be updated. The appli- cation of such an approach is demonstrated by an illustrative example.

Jan 1, 1989

By J R. Robinson

Prior to mine development, exploration drilling within the Luise Caldera on Niolam Island encountered gold mineralisation to the northwest of the main Minifie and Lienetz orebodies. This mineralisation was referred to as the Kapit orebody, and ten diamond drill holes were subsequently completed over the area to investigate its economic potential. Several significant mineralised intercepts were returned. These were interpreted using the orebody model developed for Lihir at that time which invoked a strong horizontal control to mineralisation. Additional consideration was given to the elevated geothermal temperatures encountered, the proximity of the mineralisation to the ocean, and its perceived depth below sea level, resulting in the Kapit area being given a low priority for follow up investigation. As a result, no further work was completed over Kapit until recently. The Kapit orebody was the target of an intense diamond drilling programme during 2002/2003. Data from this latest round of drilling has significantly improved understanding of the mineralisation and associated geology. The significant orebody now delineated at Kapit substantially differs from past interpretations, and the latest data has upgraded its economic potential. A resource estimate and other critical studies completed in 2003 enabled an updated reserve statement to be issued in February 2004 including the Kapit mineralisation for the first time. Total Probable Reserves at Kapit stand at 25.2 million tonnes (Mt) at 5.28 grams of gold per tonne (g Au/t), for a total of 4.3 million ounces (Moz) of contained gold.

Jan 1, 2004

Drilling and blasting operations have historically been viewed as a necessary 'evil' part of mining, whose costs should be minimised by whatever means possible. In the past, when operations depended primarily on crushing and milling for ore re

Jan 1, 1998

By Lawson F

The leaching behaviour of BHAS copper matte in oxygenated acidic sulphate chloride solutions at 85¦C has been studied using samples containing 34% copper, 41% lead and 12% sulphur. Copper sulphide in the matte, essentially Cu2S was found to leach in two distinct stages. Similar to the behaviour of pure chalcocite, copper dissolution in the first stage was affected by the availability of oxygen in solution. The presence of chloride ions in the leachant was essential if there was to be any leaching in the second stage (which usually commenced after about 40% of the copper had been taken into solution). Lead sulphide in the matte was oxidised to lead sulphate and formed a shell around the partially leached matte particles. Electrochemical studies showed that this lead sulphate and/or sulphur produced during leaching can form a passivating layer around the copper sulphide. However, this layer was disrupted when chloride ions were present. A Plackett-Burman analysis was used to determine the species in the recycled leach solution that affect the leaching of copper. Under the experimental conditions used, in the first stage the rate of copper dissolution was influenced by the concentrations of sulphuric acid, Zn(II), Cu(II), Fe(III) and Cd(II). In the second stage, the rate was futher modified by the concentrations of Cl(I) and As(V) ions. In solutions of low acidity and high As(V) concentration, insoluble copper arsenate formed which coated the partially leached matte particles and acted as a barrier to futher reaction.

Jan 1, 1989

By Lumley G. I, Hayes H

Non-intrusive methods for the reliable determination of dragline bucket and rigging performance have been achieved using physical modelling. Modelling offers a logical first step towards developing mathematical simulation models. The process of physical modelling has been applied successfully to predict dragline bucket performance and capacity as well as to demonstrate the effect of varying dump rope length on performance. ACIRL's Surface Miming Group has used physical modelling to carry out dragline bucket sizing for a new high productivity bucket and compared performance with Throng Coal's existing dragline bucket. The predicted bucket performance has since been confirmed in the field using dragline monitoring techniques.

Jan 1, 1992

By Haigh C. J

A process has been developed to recover at least 75% of the 2-naphthol contained in cobalt precipitate produced during the removal of cobalt from electrolytic zinc plant solution. The recovered material is in a form suitable for recycling to precipitate further cobalt from solution. The process consists essentially of two steps. The first involves leaching of cobalt precipitate in 400 g/l sodium hydroxide solution at 95¦C in the presence of an additive. The second step involves treating the filtrate from the leaching stage with sodium sulphide to precipitate cobalt as the sulphide thereby re- generating the sodium hydroxide for recycling. The process is only marginally profitable at present 2-naphthol prices, giving a net return of 20% on a capital investment of $1 200 000. A reaction mechanism is proposed which accounts for the 25% loss of the 2-naphthol in the recovery process.

Jan 1, 1977

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 Carlson BL, Overton DD

This paper compares the designs of heap leach facilities for four precious metal mining projects in the southwestern United States. These four proposed projects are of small-to medium-size relative to other operating mines in the United States, and are either permitted or in the final stages of permitting. The differences and similarities in the heap leach facility designs are compared with respect to site conditions, operating conditions and regulatory requirements. This comparison provides a summary of the state-of-practice for heap leach facility design in the southwestern United States and identifies current issues in project development and process material containment.

Jan 1, 1997

By Fernando N, Guang LX

Brown coal in Victoria in spite of its substantial reserves is not utilized greatly because of its high moisture content(-65% w/w). Transportation and handling costs of raw brown coal, on an available energy basis are so expensive that 93% of production is burnt for electricity generation on or adjacent to the coal deposit in Victoria. With direct firing of moist brown coal in power stations, approximately 20% of the gross calorific value of the fuse is used to evaporate the water contained in the coal. This energy is lost as vapour with the flue gas which is vented to the atmosphere. Also there is a 25% increase in flue gas volume and the size and cost of most of the units through which it passes must be appropriately larger. Since there are large quantities of water present the flame temperature is significantly reduced. For zero excess air and no air pre-heating the theoretical flame temperatures are: 609'o wow moisture 1450¦C 40% ª ª ª 1790¦C ZOO ª ª ª 1990¦C As a result of this there is a reduction in radiant heat transfer leading to a requirement for a two fold increase in radiant tube area. A boiler of much greater size and cost is thus required to house the additional tubes. Figure 1 illustrates the relative sizes of a boiler fired with 60% moisture brown coal with a boiler or similar output fed with a British bituminous coal, 14% moisture.

Jan 1, 1989

The progress of longhole open stoping (LHOS) at The Zinc Corporation, Limited and New Broken Hill Consolidated Limited (ZC/NBHC) is described. The design of a novel sloped wall longhole stoping method at NBHC which should allow the cuplete extraction of the orebody without the formation of pillars and with minimal dilution of the ore with sandfill is reviewed.

Jan 1, 1983

By Duncan B

Shortwall continuous mining as first introduced at Burwood colliery, and currently being used at John Darling, Lambton, and Corrimal collieries, is a method of coal winning which was pioneered in the Newcastle district. The system uses individual hydraulic self-advancing chocks for roof support and the coal winning operation is by continuous miners and shuttle cars. Where physical conditions are suitable the system provides a safe, efficient and economically viable basis for pillar extraction. Shortwall operations have been conducted successfully in the Victoria and Dudley seam, near the coastal fringe of the Newcastle district and are now being tried out in the more difficult conditions of the Bulli seam in the Illawarra district.

Jan 1, 1972

Measurable physical characteristics of placer deposits include both fluvial sedimentological features and their related heavy mineral suite. These two important identifiable factors are interrelated and generally compliment each other furnishing a complete geological geochemical tool in cost- effective placer evaluation. Heavy mineral suite composition and character will change downstream from the provenance area and will compliment the related sedimento logical environment. Careful attention to gold particle characterization during the exploration phase will indicate new source additions, enhance deposit evaluation techniques and greatly assist in maximizing metallurgical efficiencies. Recognition of the various characteristics within these fluvial systems should enhance the total contained geochemical suite evaluation considering a finite source. Failure to recognize and measure these two important features very frequently leads to frustrated and unrewarding placer evaluation objectives.

Jan 1, 1986