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By Mouritz M

Ventilation characteristics and the occurrence of nocturnal surface inversions have been investigated within the Mount Whaleback open cut iron ore mine at Newman in Western Australia. When winds are light and/or nocturnal surface inversions form within the pit, episodes of atmospheric stagnation can occur with resultant accumulation of dust, diesel exhaust fumes, and sulphur dioxide evolved from spontaneous combustion of pyritic shale. Nocturnal surface inversions were recorded outside the mine on more than two-thirds of nights. Inside the pit, inversions were much less frequent - occurring on roughly 20% of nights when they were observed outside - and much weaker - the maximum temperature difference being 5 C¦ over 210 m inside the pit compared with 15 C¦ over 150 m outside.

Jan 1, 1988

By Heinrich CA, Wall VJ, Walshe JL

The Porgera Gold Mine, located in the highlands of Papua New Guinea, has produced over 5 million ounces of Au, since its opening in late 1990. The deposit is located within Upper Cretaceous Papuan Platform sediments approximately 25 km south of the Lagaip Fault, and is spatially and temporally associated with the 6 Ma alkaline Porgera Intrusive Complex.

Jan 1, 1995

By K E. Barns, P J. Sharman, S A. Thomas and

This paper presents the development of a regrind facility design at BHP BillitonÆs Leinster Nickel Operations (LNO) in Western Australia. The recovery opportunity was identified from an analysis of plant operating data together with scanning electron microscope (SEM) measurements on relevant tailings streams from LNO. A laboratory procedure was developed to determine the potential recovery improvement of installing a regrind facility at LNO. The last step in formulating the process flow sheet and defining the process design criteria was to construct and operate a pilot plant, which incorporated four banks of flotation cells and an Xstrata M20 Isa Mill. Pilot plant on/off trials were used to define the expected metallurgical benefit. A prefeasibility engineering design and cost estimate was completed. Following a successful internal business evaluation, a feasibility study is currently underway.

Jan 1, 2007

By Yu H, Wan B

40 percent of the coal reserves and 40 percent of the ouput of coal in China is of thick coal seams. The sub-level caving in Yangguan has evolved together with the hydraulic supports, to provide recovery rates today of 80 to 85 percent, waste ratios less than 10 percent and daily outputs exceeding 7,000 tonnes. Matching of rate of shearing bottom coal to caving of top coal is most important to achieve "simultaneous" operations. Spontaneous combustion in the goat, gas, including in the goal, and dust, are particular safety hazards which are combatted with various stringent measures.

Jan 1, 1991

By Mowat BA, Leach TM

The Morobe Goldfield in Papua New Guinea has produced in excess of 120 tonnes of gold from predominantly alluvial sources. Hardrock gold has been mined historically at Wau (23t) and Edie Creek (40 and geological resources have been established at Hidden Valley (780, Kerimenge (360 and Hamata (30t). Numerous prospects have also been identified within the goldfield. Primary gold mineralisation is related to intrusion of dacitic to andesitic Edie Porphyry (2.4 to 3.8 Ma), often with associated diatremes, which have intruded along major regional structures. A full spectrum of deposit styles from proximal (mesothermal) to distal (epithermal) to the porphyry source is recognised. The transition between the proximal and distal styles is recognised both between deposits and within an individual deposit. The deposit styles should be termed porphyry related gold mineralisation rather than given the generic epithermal and mesothermal labels.

Jan 1, 1995

The Racecourse Orebodies at Mount Isa consist of a series of parallel steeply dipping lead/zinc/silver orebodies with a strike length of up to 1000 metres. Production from these orebodies between 13 Level to 9 Level has been by a series of cut and fill stopes in two level stages, leaving a crown pillar at 11 level. Development of the 15 level to 13 level extraction stage has recently been completed. The layout consists of a series of parallel stopes over a strike length of 1200 metres. Access to the stopes is by two declines connecting the stopes with a series of crosscuts This paper describes the basic layout with development and production methods employed.

Jan 1, 1977

By Nightingale R, Johnson B, Bensley C, Vince A, Keast-Jones R

In order to counter the massive increase in the level of near gravity material that would follow the reduction in dense-medium cyclone separation density at B.H.P. Slab and Plate Product Division's B and C coal preparation plants, "wing tank" systems to control medium density to within ¦0.005RD units have been installed. However, despite very precise density control, cyclone metallurgical performance has been less than satisfactory. The approaches taken to identify the causes of this poor performance and to justify alterations in operational and maintenance practices are presented.

Jan 1, 1987

A sequence of ultramafic units, very well exposed in Munro township in the Abitibi areal, of the Cahadian Shield, exhibit features which indicate that they are sub-aqueous extrusions. They occur within a sequence of tholeiitic pillow lavas, thin graphitic sediments. and large differentiated sills. The units range from a few metres to more than 250 m in length and less than 1 m to over 30 m in thickness. Over 60 individual units, occurring as flat pancakes on top of one another, make up a total exposed thickness of 150 m. The units have formed from a magma composed of a very olivine-rich picritic liquid carrying up,to 40 per cent olivine phenocrysts in suspension. Different units display a variety,of cross-sectional profiles. As an example of the most extreme type of profile, a typical unit 2 m thick consists of a cap of highly jointed fine-grained quenched rock, 10-30 cm thick, which becomes coarser downwards, grading into a zone composed of radiating and criss- crossing skeletal olivine crystals forming the well-known spinifex texture. This becomes even coarser-grained downwards, with "books" of parallel platey olivine crystals developing sub-perpendicular to the plane of the units. Beneath this zone, which may be up to 1 m thick, there is an abrupt transition to a cumulus-textured rock composed of rounded

Jan 1, 1973

China has at least 200 collieries suffering from the problem of instantaneous outbursts of coal and gas. Strong outbursts often have occurred in geological tectonic zones and concentrated stress areas. There are some particular characteristics of these strong outbursts, including the effects of ground stress, gas pressure and the properties of coal associated with the outbursts.

Jan 1, 1986

By Beck RW, Booth GW

Differences in the gold contents of sub-sample duplicates, derived from a single bulk sample are a function of analytical and random error, inhomogeneity within the bulk and natural variations in the distribution of particluate gold. By minimising bulk sample inhomogeneity and determining analytical precision, the residual natural variation may be modelled statistically to give an estimate of Bold particle sizes.

Jan 1, 1989

By C A. Heinrich, J L. Walshe, V J. Wall

The Porgera Gold Mine, located in the highlands of Papua New Guinea, has produced over 5 million ounces of Au, since its opening in late 1990. The deposit is located within Upper Cretaceous Papuan Platform sediments approximately 25 km south of the Lagaip Fault, and is spatially and temporally associated with the 6 Ma alkaline Porgera Intrusive Complex.

Jan 1, 1995

The Mt Muro gold and silver deposit in Central Kalimantan has been in production since December 1994. The geology is characterised by narrow high-grade lodes containing gold and significant amounts of silver. From a largely untrained workforce in the grade control department, production per crew and per geologist has tripled during the three years of production. Grade control drilling evolved from blast hole sampling to reverse circulation sampling. National geologists are trained in basic modeling procedures. A fully integrated reporting and reconciliation system was programed and implemented.

Jan 1, 1997

By Willis GM

The matte-metal-equilibria in the system Pb-Cu-S have been studied at temperatures between 720 and 920¦C by direct sampling and D.T.A. methods. These results are compared with those of other workers. The applications of such data to a continuous copper drossing process, and to a number of other metallurgical processes are discussed.

Jan 1, 1975

Erratic, though spatially localised occurrences of gold particles are a common feature of high-nugget gold systems. In many cases, gold is present as isolated or clustered, often coarse particles. The nugget effect is a part consequence of small-scale geologically controlled enrichment, and the inclusion or exclusion of gold particles from samples. Economic zones are generally contained within discrete structurally-controlled ore shoots which are surrounded by, and may include barren to low-grade background material. Problems are often encountered where small sample types (eg drill core and channel samples) of a few kilograms mass understate in situ grade by up to a few orders of magnitude, due to their general inability to represent the true gold particle distribution. This leads to uncertainty in mineral resource estimates. This contribution presents case studies where geologically-based parameters have been collected from drill core and underground faces to support grade determination. These parameters - or proxies - are based on mineralogical and/or geochemical (eg specific elemental ratios, fluid inclusion compositions and elemental correlations) criteria. Such criteria can be correlated with different grade domains to provide an indication of true grade within a geologically-controlled context. Proxies have recently been used to support resource estimates reported in accordance with the JORC Code.

Mar 1, 2010

By Morland R

Recent influence of backfill stability on stope production in the Copper Mine at Mount Isa Mines Limited is described. Changes to the mining process to improve fill stability are described, including increased focus on fill performance, modifications to extraction techniques, increased fill quality, changes to drill and blast practice, and research into backfill stability. Several case studies are described.

Jan 1, 1995

Flotation of Composite Synthetic Particles

Sep 13, 2010

Variations in delay timing can have a marked influence on blasting effectiveness and, hence, on total production costs. In single-row bench blasts, delay firing is invariably more effective than simultaneous initiation. In single-row delayed blasts, there is an optimum inter-hole delay above and below which inferior blasting results are obtained. This optimum delay is equal to the time required for each charge to just effectively detach its quota of the burden. The inter-hole delay should seldom be less than 4 ms.m-l of burden.In multi-row blasts in which holes in a given effective row are fired on the same delay, the entire burden on any effective row should be detached from the rock mass just before charges in the next effeotive row detonate. Delays shorter than this give inferior blasting results and an increased likelihood of environmental and slope stability problems. If the inter-row delay is too long, cut-offs can occur, especially where the delay unit is located outside the blasthole. For a surface delay system, the optimum inter-row delay usually varies between 4 ms.m-l and 8 ms.m-l of effective burden. The number of rows that can be fired effectively with surface delay systems (in a single blast) is limited by the threat of cut-offs. Greater interrow delays and a larger number of rows per blast can be fired to advantage with down-the-hole delay systems.There are practical limits to the timing accuracy of all available delay systems. The existence of delay time variability should be recognized and duly considered in the design of blasts.The relationship between delay timing and blasting vibrations is not discussed.

Jan 1, 1977

The title of this paper implies, and the text explicity states, that Sen and Spottiswood (1984) have found a new mineral species related to geocronite and jorganite. I believe that there is inadequate justification for this claim.The X-ray powder diffraction pattern reported by the authors exhibits a close similarity to that of geocronite, as stated by the authors, which suggests a close structural relationship at the very least. It is therefore reasonable to recalculate the results of the microprobe analysis reported by them to atomic proportions on the basis of the geocronite formula. This calculation, whether based on the formula used by Sen and Spottiswood (1984), or on one derived from a crystal-structure analysis (Birnie and Burnham, 1976), namely Pb18 (Sb, AS)11S46, with a total of 86 atoms, gives the results shown in Table 1.

Jan 1, 1985

Inpit tailings disposal has been undertaken at a number of mining sites within Australia. This paper presents a brief history of the experience of inpit tailings disposal at the Marymia Gold Operation in Western Australia, including geotechnical aspects of the design. Regular monitoring of the inpit tailings disposal into the K1SE Pit at Marymia has allowed the operators of the mine to assess the performance of the tailings storage against its predicted performance during the design phase. Results of this monitoring indicated that the predicted performance was exceeded and the results have been incorporated into the design of another large inpit tailings disposal, the K1 Pit. Monitoring of tailings disposal to both the K1SE Pit and K1 Pit has allowed the mine operator to make substantial savings from inpit tailings storage when compared with above ground tailings storage facilities. The inpit method of tailings disposal at Marymia has proven to be acceptable from an environmental perspective by reducing the water resource requirements of the project, backfilling pits, which would otherwise collapse with time and eliminating the need for disturbing additional areas of mining leases, which usually accompanies construction of above ground tailings storage facilities.

Jan 1, 1999

The main factors which influence disposal of mine waste under New Zealand conditions are identified and discussed: namely, geological conditions which produce soft weather-sensitive waste, wet and cold winters which affect productivity in such waste, elevated seismicity which affects stability and the need for water rights which involve public participation. The waste disposal scheme for the Martha Hill Project is described, thereby illustrating how these factors influence the planning of a current mine strippings and tailings disposal scheme.

Jan 1, 1986