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By Bhattacharyya A. K>

The Pemali Open Pit Mine is situated in a small island called Bangka in Indonesia. It produces approximately 165,000 m3/year of tin ore with an average grade of 3.67 kg/m' of tin from a primary deposit. The deposit occurs at the rim of a granitoid intrusion within sedimentary beds. The rock formations, all extremely weathered, and the overlying alluvium, are exposed to a rainfall exceeding 3m/year. Serious slope stability problems are experienced at the mine, despite using overall pit slopes of 20¦-29¦, the latter resulting in a stripping ratio of 4:1. This paper outlines a computer based back analysis of a major slope failure involving some 250,000 m' of material which occurred on the west wall of the pit in February, 1984. The findings from the analysis, together with other information, are used to examine the stability of the east wall of the pit, where tension cracks developed later. The results indicate that the large influx of water was the most significant cause of such slope stability problems and a more intensified water management programme would be beneficial.

Jan 1, 1989

By Kurihara K, Tanimoto C

Construction and mining sites are often subject to unexpected flooding and extensive delays may occur in locating and installing emergency pumps. This particularly applies to sites located in remote areas. A simple and effective pump, called an air-lift pump, can be built from the equipment available at the working site. The basic req- uirements are a compressed air supply, air hose and conventional water pipes. The air-lift pump is comparatively in- efficient but approximately 35 per cent of the available compressed air power at the site can be applied to pumping. Suprisingly high liquid discharge rates may be obtained in suitable applications. The theoretical and practical consider- ations of the air-lift pump are evaluated and a suggested procedure for the emergency design and construction is outlined. INTRODUCTION. Sudden inundations of water into mine and development excavations require the immediate removal of the water if extensive and often irrepairable damage is to be avoided. Pumps installed in shafts or tunnels may become un- servicable due to being totally submerged during the flooding. The emphasis is on rapid

Jan 1, 1976

EnergyAustralia is a state-owned corporation in the state of New South Wales, whose responsibility includes ownership and management of an electricity distribution network. Expansion of the high voltage distribution network in the Sydney central business district (CBD) includes the requirement to run an additional five 132 kV feeders over 1.7 km from south of the CBD to a new 132 kV substation in the northern section of the CBD. A driven tunnel is currently being excavated in Sydney sandstone beneath Darling Harbour to contain the new 132 kV feeders. Tunnel construction methods involve both roadheader and tunnel boring machine (TBM) excavation. This paper describes the design development of the cable tunnel, discusses the use of a geotechnical baseline report as an integral part of the contract documentation and provides an update of the current construction works.  

Jan 1, 2008

By Morris P. H

A trial embankment was constructed using coarse coal mine reject on a deposit of crusted coal mine tailings at New Hope Colliery, located in the Bundamba District of the West Moreton Coalfields in South East Queensland, Australia. The purpose of the trial embankment was to assess the load carrying capacity and settlement behaviour of the crusted tailings, including an assessment of strength gain in the tailings under the influence of the fill. Prior to construction of the trial embankment, a site investigation of the tailings deposit was carried out. This comprised vane shear strength testing, together with disturbed sampling and undisturbed block sampling for the purposes of laboratory testing. Following the site investigation, settlement plates and standpipes were installed at various depths and locations within the tailings in the vicinity of the proposed embankment. The instrumentation enabled the magnitudes and distributions of settlement and pore pressure within the tailings to be determined during and following construction of the embankment. The embankment was constructed using coarse reject in three equal lifts to a height of 3.0 m. The tailings sustained a maximum settlement under the weight of the fill of 290 mm, representing about 4.2 ii of the average initial thickness of the tailings and a loss of embankment height of about 9.7 %. By the end of the monitoring period the strength of the softer tailings underlying therust had roughly doubled under the influence of tha cmbarikment

Jan 1, 1990

By Wilkinson RDB, Van Der Meer FP

In order to overcome the statistical limitations imposed by the need to recover density tracers by hand, magnetic density tracers were developed to determine the efficiency of dense medium separators treating porous materials. The tracers were manufactured by extrusion of polypropylene ferrosilicon mixtures and subsequently coated with a distinctive paint to allow hand sorting according to density. Fifteen tracer batches were manufactured in the range 1.61 - 1.94 g/cm3. The tracer densities were determined by a hydrostatic method. The tracer method was applied to the dense medium separation of a Moroccan oil shale in a pilot scale Dyna Whirlpool separator. For each test, about 20,000 tracers were added with the plant feed and subsequently recovered from the products with a dry low intensity magnetic separator. The Tromp curve determined by conventional heavy liquid analysis was displaced towards lower densities compared with that determined by tracers, indicating that the porous shale particles absorb heavy liquid. It is concluded that for porous materials like oil shale and coal, the tracer method gives the most accurate results. In pilot scale testwork the tracer method is also much faster than the conventional heavy liquid analysis, as rather large samples have to be processed by the latter method to ensure Representativeness.

Jan 1, 1987

Introduction The mine winder is an essential element in the mining of ore in deep level mines and therefore requires a high degree of reliability to avoid interruption of production. Failure of any component on a winder may also be dangerous and expensive to repair. The larger the failure the larger the stoppage. The failure of a winder drum is the ultimate catastrophe, not only because of the cost of replacement, but also because of the lead time in procuring a new drum. Today these types of failure are not as common but many failures have occurred in the past and even today many an old winder is con- sidered for a new and often more arduous duty. As far back as the turn of the century a lot of information had been gathered to try and clear up the complexities of the multi- layering effect of coiling rope under tension onto a drum. Before comparing results obtained by various researchers the nature of the pressure distribution between rope and drum due to multi-layering will be discussed briefly.

Jan 1, 1987

By Walker G. S

Infrared and Raman spectroscopy have been used to study a range of solid state and aqueous solution species which are of interest in extractive metallurgy. In the solid state new Cu(II)/CN'/NH3 complexes have been detected, iron impurities in kaolin characterised, aluminium substitution in hematite and goethite quantified, and the crystallinity and orientation of zircon determined in heterogeneous crystals. In aqueous solution metal cyanide complexes and equilibria were readily characterised, the thermal decomposition of SO2 monitored and products identified, and complexation of AI(III) by hydroxycarboxylates observed. Attempts to monitor the early stages of the gelling of silicate solutions were less successful, with only changes in the gel being detected. However, the degradation of 12-tungstosilicic acid was readily monitored as a function of both time and pH.

Jan 1, 1996

By Allchurch P. D

At Perseverance a reserve of 45 million tonnes at 2% Ni was indicated by drilling. Holes were drilled in trellis pattern on section lines 61m apart to assess shallow mineralization. To explore at depth holes were spaced 122m apart, collared vertically, then allowed to deflect under controlled drilling conditions. The mineralization may be divided into the three homogeneous classes of soarsely disseminated, heavily dissem- inated and massive sulphides. In the standardised sampling and assaying procedures used to assess the deposit, attention was always paid to these fundamental ore types. All sampling and assaying processes were continuously monitored by checks. Sampling and sample preparation errors were small, to judge from the differences between results of original and check samples. Assaying errors, determined from analyses made by independent laboratories using different methods, slightly exceeded sampling errors. Comparison of underground core, c'iannel, and grab sampling, suggests that core sampling tends to undervalue.

Jan 1, 1976

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

This paper carries on from an earlier paper 'Cemented fill practice and research at Mount Isa' and reports further on the laboratory programme at Mount Isa to develop a cheap cem- ented fill using Company waste products. The practical economic significance of availability of cheap cementing agents is re- viewed, with the various alternative approaches available The basic approach adopted within this paper is that use of reactive pozzolans such as ground slags to replace a proportion of the Portland cement in the fill can make mining methods employing cemented fill more economic- ally competitive with other mining methods.

Jan 1, 1973

Copper refining electrolytes are maintained in the range 60-65¦C to ensure an efficient operation. The heat energy required to meet these temperatures has been traditionally derived from the electrical energy required for the electrolytic process and supplementary steam energy. In 1983, experiments were conducted at Copper Refineries Pty. Ltd. (CRL) to determine the effects of insulating the Tank House cells, and fully covering the cells. The results of these experiments showed conclusively that greatly reduced steam consumption would be required to maintain electrolyte temperatures. These positive results led to an Energy Conservation Programme for the Tank House, and this was implemented in 1984. A computerised cell cover monitoring system was developed, and is used to control cell coverage and fluid balance. The experimental work and the benefits obtained since implementation of the programme are discussed.

Jan 1, 1985

Epicentres of recent shallow earthquakes in the region (3-12¦S, 126-150`E) were plotted to identify the various plate boundaries in the region, in particular the southernmost one marking the northern edge of the Australian plate. New and published fault plane solutions were examined to determine the style of faulting and state of stress along the Australian plate boundary. From east to west the boundary is first a subduction zone along the Solomon Islands, then a spreading centre across the Solomon Sea, a zone of compression and left lateral strike slip along the Papua Peninsula, almost pure thrusting across the centre of New Guinea and lastly left lateral strike silo through Irian Taya to the outer Banda Arc. The principal stress is very consistent, trending NW to NNW in a near horizontal plane, from the triple junction of the Pacific, Solomon Sea and Australian plates in the east to the Banda Sea in the west. Only along southern Solomon Sea plate margin which is a divergent boundary, is the stress different in type and direction.

Jan 1, 1987

By Brinkmann J. R

The relative effects of the two basic mechanisms contributing to rock breakage during blasting, shock and gas penetration, are neither well understood nor well characterized, and need further clarification. Blasthole liner (BHL) tests separate the two effects, and by enabling direct measurement of borehole expansion give insight into the shock/gas energy partitioning in rock confinement. The hydrodynamic code DYNA2D is used to simulate the shock effect of the detonation of emulsion in a stainless steel lined hole, and the predicted expansion is compared with experiment. Workers in the past have neglected near-blasthole phenomena and have calibrated models based on stress measurements remote from the blasthole. Extrapolation back to the blasthole has inherent limitations, and indeed, one of the deficiencies of these models is that they have not been able to predict correct borehole expansions, as observed in BHL experiments. DYNA2D has been enhanced by the ICI group with a detonation model which resolves the explosive reaction zone. As a preliminary step towards the ultimate goal of devising a practical damage model, simulations are used to predict the maximum expansion that would take place if the rock were to remain undamaged. Various material parameters are investigated and it is shown that calculated liner expansions are appreciably lower than measured values for high rock yield strengths, while greater than values for low yield strengths.

Jan 1, 1990

By Daziel M, Corke P

Unit cycles in mining have not changed for many years. Productivity increases over the past three decades have mainly been achieved by using larger and heavier machines. This investment in size has probably reached the point of diminishing returns and increased productivity in the future will have to be generated by other means. One way of achieving this is through automation of selected unit operations, eg dragline overburden removal, truck haulage, ground support installation and secondary breakage. Although, in the past few years, there has been significant progress in this direction, we are still a long way away from even partial automation - especially in hard rock mines. This paper addresses the technical obstacles facing mining automation; suggests ways by which these obstacles may be overcome and identifies the role of industry groups and research providers in this process.

Jan 1, 1997

By Abrahamsson S, Niklasson B

In a follow-up of 12 production blasts in a quarry at the Mrica project on Java, tightly spaced porous bands were found to govern fragmentation to the extent that the average fragment size k5o was nearly independent of the specific charge within the range 0.30-0.56 kghn3. This fording resulted in a reduction of the running costs for drilling and blasting by 20-40%. Our work has given considerable practical benefits and insights into the blasting process, even if the results were of no direct use to check out fragmentation predictions based on models, which was one of our main Goals.

Jan 1, 1990

This report chronicles the historical development of longwall mining in the United States and speculates on future developments to the turn of the century. Five eras of technological development during the modern period are described and analyzed. These eras discuss the development of (1) mechanized extraction, (2) self advancing roof supports, (3) high capacity roof supports, (4) shield supports, and (5) system automation. Current trends are analyzed in terms of: longwall utilization, production capability, support capacity, face widths, and new technological developments. From these analyses, the future of longwall mining to the year 2000 is speculated. It is concluded that longwall mining will continue to grow in importance during the next decade and that the next major technological milestone will be the realization of a fully automated longwall mining system.

Jan 1, 1992

There is considerable economic incentive to increase the angle of open pit walls so as to reduce the total volume of waste to be moved to gain access to an orebody. However, a number of slope failures has increased the awareness of mine operators to the potential and consequences of slope failure. Sophisticated methods for the analysis of slope stability have been developed but they rely on an understanding of the appropriate parameters to describe the structural properties of the slope materials. Unfortunately, these properties change with time.The excavation of an open pit mine removes the constraint and weight of the overlying material and allows the newly formed slope to release previously locked in stress. The release of this stress allows the opening of joints and leads to a significant reduction in bulk modulus. The rock mass is also further affected by damage from nearby blasts. Such damage is cumulative and further reduces the modulus of the near surface material and weakens the bonds between structural elements in the slope.

Jan 1, 1992

By Clappison D. J

Since its formation in Papua New Guinea and raising of A$2 million in 1980, Niugini Mining Limited (NML) has grown to a company capitalised on the Australian Stock Exchange at about A$350 million. In 1995 the company produced some 237 000 ounces of gold, 700 000 ounces of silver and nearly 5000 tonnes of copper from its operations at Red Dome, in North Queensland and San Cristobal in The Atacama Desert of Northern Chile. This production contrasts with Niugini Mining's first mining venture at Mt Victor in the Eastern Highlands of PNG which yielded 20 000 ounces of gold and 11 600 of silver between 1987 and 1989. Following the formation of an exploration joint venture in 1982 with Kennecott Explorations (Australia) Ltd, now a subsidiary of RTZ, Niugini Mining's early recognition of the gold potential of volcanic rocks at plate margins led to discovery of the Lihir deposit in July 1982. This deposit containing about 42 million ounces of gold in resources, is one of the largest undeveloped gold deposits in the world. Following raising of equity funds through the float of Lihir Gold Ltd and debt finance in 1995, construction of the mine at a cost of US$673 million is now underway with first full-scale production at approximately 600 000 ounces of gold per year expected in early- 1998.

Jan 1, 1996

By Takagi T, Seetharam R, Sie SH, Naito K

Tin-polymetallic vein type deposits are one of the major source of metal producers in the Circum Pacific Belt. This type of deposit is of great importance for the modem electronics and medical industries because of their high content of rare metals (especially indium and bismuth). We have studied two representatives, Tosham of India (Cu-In-Bi-Sn-W-Ag-Au), and Mount Pleasant of Canada (Zn-Cu-In-Bi-Sn-W), using proton and electron microprobes in order to delineate the distribution of medical/high-tech rare metals. The electron microprobe study showed that major indium carrier in such type of deposit are roquesite (CulnSZ), sphalerite, stannite and a Cu-Zn-Fe-In-Sn-S mineral; and that indium is incorporated in sulfides by coupled substitution like Cu + In = 2(Zn + Fe). The proton microprobe showed that indium at trace levels is also present in chalcopyrite and pyrite. In addition, zinc, copper, arsenic, antimony, selenium, tin, and bismuth are common in chalcopyrite and pyrite. Arsenopyrite contains nickel, copper, zinc, silver, tin, antimony and bismuth. In chalcopyrite and pyrite, zinc, arsenic, indium, bismuth and lead are higher in Mount Pleasant ore, but silver is higher at Tosham. Also thallium and gold were found only in Tosham pyrite. The Tosham deposit is genetically related to S-type magma, while the Mount Pleasant deposit is related to A-type granite. Tosham ore contains zinc-bearing biotites that coexist with chalcopyrite in ore bodies but Mount Pleasant ore lacks such biotite. We propose that the difference in elemental abundance between the two deposits are caused by the different character of source magma and different mineral associations of the ore body.

Jan 1, 1995

By Wygralk A, Hallenstein CP

On a world scale, many Mid-Proterozoic fluvial sediments are prospective for low grade, large-tonnage gold deposits. A significant area of the Northern Territory is covered by such Mid-Proterozoic sediments, the gold potential of which has been barely tested. The geological knowledge of these sediments is summarised. The Westmoreland Conglomerate, the basal Mid-Proterozoic formation of the McArthur Basin, has been subjected to detailed sedimentological studies in order to determine the paleoenvironments and to assess the possibility of paleoplacer occurrences. The results indicate that the sandstones and conglomerates of the formation were deposited by braided rivers and debris flows as an alluvial fan which originated in source areas to the north east. The formation contains several upward-fining cycles of sedimentation, which are related to repeated periods of uplift in the source areas. The formation of placer-type gold occurrences is possible in such depositional environments. Very limited heavy mineral sampling has indicated a cassiterite- wolframite-gold suite in the sediments of the Westmoreland Conglomerate. Disconformities at the base of sedimentation cycles are deemed to be the most likely sites for large-tonnage paleoplacer concentrations.

Jan 1, 1984