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The mineral sands deposit of Australia pose a number of unique, and quite unusual problems for the explorationist. Most concentrations of heavy minerals have been found in the unconsolidated sediments of the east and west coasts. Mineral sands mines open larger areas per tonne of concentrate than most other mines. This is because of the shallow depth of the sands containing the heavy mineral concentrations. Obtaining tenure can, by mining industry norms, be a massive operation due to the large areas to be examined and, particularly on the east coast, the large number of land holders encountered. A commercial development can still emanate from anything ranging from a small high grade body to a massive low grade deposit, the prices currently being obtained for rutile, zircon, ilmenite and monazite, although still modest when the remarkable properties and applications of these minerals are considered, is nevertheless attractive when compared to the prices being obtained for the base metals with the exception of gold. The current interest in the location and definition of new reserves of heavy minerals reflects this relative price attractiveness. The discovery of heavy mineral concentrates does not necessarily ensure the early establishment of a mine. Because of the cyclical nature of market prices, the average returns likely over the life of the mine permit the employment of only relatively simple, low cost, mining, concentration, and separation processes. If difficult mining conditions are encountered or the removal of small contaminants by complex metallurgical processes are required, then higher market prices must be obtained. Until the market is prepared to pay more for the commodities so produced, the resource will not be economic and lower cost reserves will be mined in preference. The Australian mineral sands industry has seen many closed mines because of past failures to properly assess the data base collected during the exploration and development phases of the failed projects.

Jan 1, 1987

By Baafi EY

Open cut mining in Australia is facing the greatest challenge in its history in attempting to compete not only with other operations internationally, but also with underground operations domestically. Most flat dip and shallow depth surface-mineable coal reserves have been depleted during the last two decades and new open cut operations must extract deeper coal deposits. As open cut coal mines move into deeper areas and the stripping ratios increase, the relative cost of overburden removal also increases. It therefore becomes even more important to design the mine around the optimum overburden removal scheme. The deeper mines are usually multi-seam operations with a more complex geology and with more geotechnical and hydrological problems. Deeper mines are subjected to greater problems requiring more detailed mine planning and design, such as selection of the optimum mining method and pit layout. In planning and design of such operations, the number of alternative methods which need to be considered is consequently greater.Dragline productivity and its stripping capabilities are directly affected by the selection of digging method, strip layout and pit geometry. Every mine has a unique combination of geological conditions. The operating methods that work well at one mine may not necessarily work at another site. Selection of an optimal stripping method, strip layout and pit geometry for a given dragline must be considered with respect to the geological conditions of the mine. With increasing geological complexity of Australian strip mines, it is becoming more important to use sophisticated techniques such as computerised mine planning methods to assist in optimising dragline operations.

Jan 1, 1998

By K C. Corin, C T. O’Connor

In recent years it has been shown that the concept of using partial molar excess Gibbs energy (G̅ex) to explain the behaviour of collectors in the recovery of minerals can be usefully applied to explain flotation performance. Fundamentally this is because hydrophobicity of a mineral particle on which a collector is adsorbed may be strongly related to the fact that the alkyl chain associated with the collector behaves in the same way as any hydrocarbon would in an aqueous medium. This hydrocarbon-water system represents a classical non-ideal mixture, and such mixtures are quantified thermodynamically by determining the activity coefficient of the hydrocarbon moiety of the collector and hence its G̅ex in the mixture. It has been shown that G̅ex is a more rigorous indicator of the contributions of various alkyl groups of a collector than HLB (Corin and O’Connor, 2014) and was also able to explain aspects of froth behaviour (Harris and O’Connor, 2017) and hydrophobicity (O’Connor, 2021). The present paper is aimed at extending the above concepts in two different ways. Firstly, a study is undertaken of a range of results previously reported in which various reagents containing different alkyl groups were analysed in terms of their effect on contact angle and their performance as flotation reagents in terms of recovery. These results sustain the previous observations that there is a robust positive relationship between hydrophobicity as indicated by flotation recovery and contact angle and G̅ex of the alkyl group associated with the collector. Secondly, on the basis of the observation that increases in G̅ex are indicative of increases in the hydrophobicity of the mineral particle-collector aggregate, a study was undertaken to examine the effect of ions typical of electrolytes in water as well as the effect of the presence of alcohols and of pH on G̅ex of the collector alkyl group. In the former two instances the absence of any correlation between G̅ex and recoveries supported the proposition of the respective authors of these studies that the major effect of these electrolytes and added alcohols may be on particle–bubble attachment rather than on the hydrophobicity of the mineral/collector in the aqueous system. On the other hand, the effect of pH on G̅ex correlated reasonably well with changes reported in the literature on the effect of pH on recovery and contact angle.

Aug 24, 2022

By J Hadjigeorgiou, T R. Stacey

A ground support system is a combination of individual reinforcement and surface support elements that work together to retain and contain the rock mass. The various elements are subjected to external loads and to interactive loading between individual ground support system components. This paper focuses on the challenges in determining the capacity and behaviour of mesh, recognizing that installed mesh can be subjected to several loading mechanisms. Field observations from underground hard rock mines demonstrate that there are multiple types of damage and modes of failure of mesh. However, these are difficult to reproduce in a laboratory environment. A critical review has shown that existing mesh laboratory testing rigs reproduce very limited loading conditions that may not be representative of underground conditions. This has significant implications in quantifying and extrapolating the performance of mesh to ground conditions. CITATION:Hadjigeorgiou, J and Stacey, T R, 2018. Challenges in determining the capacity of mesh, in Proceedings The Fourth Australasian Ground Control in Mining Conference (AusRock), pp 280–290 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 30, 2018

By S Azam

Coal is a vital energy source and source of carbon for metallurgical applications, contributing significantly to the world economy. Coal mining and processing involve multiple processes that generate Respirable Coal Mine Dust (RCMD), one of the primary sources of health hazards for coal workers. Since 2000, the rate of Coal Workers’ Pneumoconiosis (CWP) has continually increased in the U.S, with severity of the cases also worsening. Increasing evidence shows that exposure to RCMD in coal workers is a high-risk factor for lung cancer, which causes more deaths than the following three major cancers combined in the US Recent observations show an increased incidenceof CWP or other lung diseases, particularly among young miners in the Appalachian basin. The CWP prevalence in Appalachia is four times higher than the national average. Although various regulations are in place, the resurgence of such disease among coalminers demands additional efforts to better understand all the possible facets of coal dust toxicity, taking insights from current interdisciplinaryresearch efforts. One such important field is the interaction of coal dust with moisture in underground mines. Although moisture is prevalent and dynamic in an underground mining environment, it has never been evaluated for its impact on modifying the toxicity of coal dust and transport or flow behaviour. However, research conducted in atmospheric sciences in the past decade makes it clear that moisture in the atmosphere can significantly alter the behaviour of mineral dust. This paper is a part of research aimed at understanding how moisture interacts and alters the characteristics of coal dust. Such insight is crucial in understanding the potential toxicity of coal dust and developing mitigation technologies.

Oct 12, 2022

The Hunter Fracture Zone can be traced into the Fiji group, and onshore SE Viti Levu in the form of NE-trending morphostructures. NW- trending morphostructures offset the NE elements. Structural mapping of Suva Harbour indicates that the NE elements are grabens bordered by faulted monoclines. Faulting is characterised by block-rotations and dip-slip displacements. The NW morphostructures are faults displaying elements of both dip-slip and strike-slip movement. Structural overprinting suggests that the NW faults represent the youngest phase of deformation, and current seismic activity occurs on this trend. A conceptual, geomechanical model of the deformation invokes toppling and wedge failure at the edge of the Fiji platform, translating material downslope into the Hunter Fracture Zone. The interference pattern produced by the superposition of the NW on the NE structures consists of a series of circular features bearing superficial resemblance to volcanic centres. Known mineral deposits in SE Viti Levu correspond closely to these features. The formation of the circular features postdates mineral genesis, suggesting that the features provide a focus for the enhanced exposure of mineral deposits rather than a source of mineralisation. There is a close association between mineralised exposures and interference patterns in extensional structures in SE Viti Levu, and a correlation between these structures onshore, and the Hunter Fracture Zone cum South New Hebrides Trench offshore. Future mineral exploration in the SW Pacific will benefit by closer consideration of the geologic structure of Pacific islands bordering the extensional regimes of deep oceanic trenches.

Jan 1, 1987

By S Farrokhpay, M Zanin

Although it is well understood that in flotation collection zone and froth zone are deeply interconnected, and reagents (and in particular collectors and frothers) cannot be selected without considering their synergistic effect, this concept is rarely applied in plant practice. The feed mineralogy also has an important role in how particles and reagents interact in flotation, which is sometimes overlooked by operators. In this work, a combination of batch flotation tests and froth stability measurements was used to optimise the collector and frother scheme for the flotation of a copper ore. The methodology was applied to an Australian copper plant which was experiencing high variability in froth stability in the roughers when the feed ore mineralogy was changing. It was hypothesised that chalcopyrite in the feed in combination with isobutyl-xanthate had a destabilising effect on the froth phase under the reagents scheme used. Froth stability was restored if a shorter chain length, less hydrophobic, xanthate was employed. It is apparent that the hydrophobicity of adsorbed films at the solid/liquid/air interfaces has a critical role in enhancing or reducing froth stability. Unstable froth causes a reduction in copper recovery in spite of a high collection zone flotation rate. The case study suggests that collection zone and froth zone can rarely be optimised independently of each other. With the laboratory procedure adopted, a more suitable reagents scheme was determined to respond to changes in the feed mineralogy, avoiding fluctuations in plant performance due to unexpected froth instability.CITATION:Farrokhpay, S and Zanin, M, 2012. Synergic effect of collector and frother on froth stability and flotation recovery - An industrial case, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 145-150 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By R A. Pax

Operational grinding mills emit significant acoustic emissions which are a consequence of the dynamic environment prevailing inside them. From a technical perspective, the noise presents an opportunity to determine some details of the processes occurring inside the mills. The noise generated is not random and can be attributed to a range of events that occur inside these mills, consequently non-contact acoustic determinations of in-mill behaviour provide powerful insights into the operation of primary comminution tumbling mills. To enable a logically coherent picture to be formed of the processes inside a mill, arrays of microphones have been used. This approach allows a clearer picture of the in-mill behaviour of the charge to be accessed. In contrast to single microphone approaches, usually located near the expected charge toe position, an array of microphones allows much more useful information to be obtained from grinding mill noise.This paper will discuss and present data obtained from microphone arrays positioned at the toe and shoulder locations of a mill, and how this information can then be used for the optimisation of grinding mills in real-time.CITATION:Pax, R A, 2012. Determining mill operational efficiencies using non-contact acoustic emissions from microphone arrays, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 119-126 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

East Nelson and Marlborough, in the northeast of the South Island, contain a wide variety of metallic minerals, including gold, silver, copper, chromite, antimony and scheelite, but no sustained metallic mining industry has evolved. Gold was the most sought-after mineral during the first century of European settlement and numerous discoveries were made but these failed to live up to expectations. While traces of gold are widespread in east Nelson, including in quartz veins in Nelson City, no payable deposits were found. In Marlborough the probability of a gold discovery had initially seemed remote but all this changed with the finding of rich deposits in the bed of the Wakamarina River in 1864, which provided a much-needed boost to the provincial economy. However, the decline of gold mining in Marlborough began virtually as soon as it had commenced. Extensive floods in 1865 hastened the exodus of miners to the profitable new fields of the West Coast.

Jan 1, 1993

By Gao K, Wu C, Langley J. M, Waugh B, Farrell K

The dissolution of carbon from carbonaceous materials into molten iron is a key step in various ironmaking operations. For example, in new direct smelting processes, carbon in the form of coal is injected into the molten iron bath, which leads to the dissolution of carbon. In foundry operations, typical recarburizer materials can range from high purity graphite to chars. The dissolution performance of these" materials is critical to the operation and could dictate the efficiency and economics of the process.Dissolution kinetics has been studied by various investigators to explain the influence of melt conditions and carbon type (Sahajwalla et al, 1994; Shigeno, Tokuda, and Ohtani, 1985; Orsten and Oeters; 1988; Ganguly and Reid, 1992; Wright and Taylor, 1993). The influence of melt sulphur content on the dissolution kinetics has been characterised (Sahajwalla et al, 1994), with sulphur retarding the rate of carbon dissolution. The carbon dissolution from different sources is seen to vary significantly even under similar melt conditions. This observation has been explained by investigators on the basis of the varying ash content present in the carbonaceous materials. However, ash content alone cannot account for the variability in dissolution kinetics reported in other studies. One such study is presented below.In a recent study (Sahajwalla et al, 1994), pulverised carbonaceous materials were injected into the molten iron bath and the" dissolution kinetics was established. The dissolution of graphite and glassy carbon, which contain almost 100 per cent carbon, was seen to be significantly different when the molten iron contained sulphur. The influence of melt sulphur content was explained on the basis of different wetting behaviour observed.Importantly, the study showed that even pure carbon sources dissolved at significantly different rates. Hence, their performance could not be explained on the basis of ash content.The key difference between graphite and glassy carbon is in their atomic structure. Graphite is highly ordered whereas glassy carbon has relatively poor ordering in its atomic structure. This study showed that the atomic structure in carbonaceous materials can have a significant effect on their dissolution performance.The focus of the present investigation which stems from the past study described above (Sahajwalla et al, 1994), is to investigate the influence of atomic structure of carbonaceous materials on their dissolution into Fe-C-S melts.The specific objective of this study is to determine the relationship between dissolution kinetics and crystallographic character of carbon sources. In order to accomplish this goal, a range of different materials representing a spectrum of carbon sources have been chosen for the investigation. These materials include brown coal char, two types of Auscarb (A and B), and commercial graphite. Auscarb is prepared by calcining Auscoal at 1000°C. Auscoal is made from chemically cleaned Australian coals (Bowling, Chandler and Waugh, 1990). Part 1 of this paper details the dissolution performance of the materials studied, while Part 11 describes the X-ray diffraction study. The relationship between the atomic structural dimension and dissolution rate constant is discussed in light of the results obtained.

Jan 1, 1996

The use of scrapers in mining and earthmoving operations is not new; in fact they are one of the earliest methods of bulk earthmoving. A single machine, which can load, haul, and dump material with a minimum of ancillary support is a highly productive and cost-efficient method of earthmoving. In recent times scrapers have been unpopular due to perceived problems and operational limitations, but the last couple of years have seen a resurgence in the use of scrapers in the Bowen Basin as a primary prestripping tool. The main operational limitation of scrapers is the economic operating range. Maximum productivity and lowest cost per bcm is achieved on short leads, as the lead distance increases the cost per bcm quickly reaches and then overtakes that of an truck-excavator fleet. The geometry of a ætraditionalÆ coal mine does not readily allow short leads for prestrip fleets due to the nature of dragline stripping operations. The strip arrangement means that material has to be taken around the end of the pit, meaning a longer haul distance than the actual point-to-point distance between load and dump. This can be alleviated by using pit bridges, however these can cause spoil problems for draglines if not properly planned and have been avoided by many mines. Due to the economic haul distance limitation of scrapers, truck-excavator fleets have become the normal method utilised. Currently more geologically complex mines are opening up, which do not allow traditional down-dip strip mining to occur. Cross-dip mining methods allow for short leads between prestrip loading and dumping areas, hence scrapers and bulk doze are realistic alternatives to a truck-excavator fleet in the prestrip environment. Keeping the lead distance to a minimum a fleet of 657Æs can move material at a very low cost. The other main operational limitation of scrapers is the type of material that can be economically excavated. Hard material can lead to damage to the bowl, free-flowing sand will not readily stay in the bowl leading to reduced load factors. Ripping the material with a dozer prior to excavating can lead to improved loading time, and greatly reduced GET consumption. When considering scrapers for prestrip operations a number of things must be considered: is the lead distance within the economic haul distance? should twin power (push-pull) or single power (dozer pushed) scrapers be used? do I need to rip, what should I rip with? what ancillary support is required? is there another system already available on-site which is currently under utilised? This paper considers the parameters under which large twin power scrapers are the most effective way of undertaking prestrip operations.

Jan 1, 2003

By J I Stewart

The Copper Canyon deposits, occur in proximity to the regionally distinctive formational boundary between the Staveley Formation and Marimo Shale. The mineralisation here is associated with breccias, veins, and alteration zones near the base of the Marimo Shale unit and in the underlying evaporitic dolomite-dololutite dominant Staveley Formation. The Marimo Shale unit, in its basal 60 metres, is highly carbonaceous and hosts ubiquitous but minor diagenetic (?) copper-pyrite, and on occasion, extensive albite-microcline alteration centres, pyritic (cobaltiferous)-quartz veins, and microcline-quartz_+plagioclase veins or veinlet arrays. The most significant mineralisation, such as at the Greenrnount prospect, consists of a shallowly dipping package of alteration zones overprinted by multiple generations of pink-orange microcline-quartz-chalcopyrite-pyrite-(arsenopyrite) and albite-calcite- phlogopite veins. Accessory mineralogies in most of these mineralisation styles consist of tourmaline, monazite, rutile, and apatite. Chalcopyrite (and secondary chalcocite) and gold are associated with each generation of alteration but are best developed in the later stages of veining. In the underlying Staveley Formation, which is a conformable transition between the Corella Formation limestones and the Marimo Shale, chalcopyrite (cobaltiferous)-pyrite mineralisation occurs as disseminations in pre- and syntectonic breccias, and with disaggregated silica pseudomorphs (after thinly bedded evaporitic sulphate beds) and associated dolomitised limestone-calcilutite. Although this mineralisation may be partly diagenetic in origin the 200 in thick evaporitic packages are also host to a locally widespread (2 to 4 km long and 200 to >500 metres wide) and pervasive 'redrock' styled microcline-dolomite¦hematite alteration. Within this gross alteration package there also seems to be a consistent association with narrow (10 to 100 metres wide), linear (stratabound) semi-massive magnetite-hematite-microcline and quartz-chalcedony replacement zones. Like much of the nearby Corella Formation the Staveley Formation, under the Marimo Shale, has undergone dissolution, paleo-solution karsting (breccias) and tectonic brecciation such that the precursor lithological details have been progressively obliterated. The post-diagenetic to post-tectonic fluid pathway development and metasomatic alteration history of this important lithostructural package of rocks has been traced from preliminary studies only. The ability to do so is largely due to the absence of significant regional and contact metamorphic overprinting, and the local preservation of precursor sediment profiles. It is proposed that both the base of the Marimo Shale and parts of the underlying evaporitic-limestone-dololutite have acted as conformable fluid pathways for hydrothermal and (perhaps) diagenetically derived, Cu-Au-(¦Co ¦As) K-Na-Ti-REE bearing, fluids and brines.

Jan 1, 1994

By Hilde TWC

Synthesis of GLORIA side-scan sonar and other geophysical data has provided morpholo- gical and tectonic details of the interaction between the Nazca and South American plates along the Peru Trench (80S-15¦S). Our analyses suggest that a new propagating rift of the Galapagos type is evolving along the Mendana Fracture Zone (MFZ). Subduction induced rift- ing of the Nazca plate is accompanied by organized seafloor spreading for the last 3 Ma at least. GLORIA sonographs and bathymetric mapping show an 8-10¦ divergence in MFZ width towards the Peru Trench. The fracture zone comprises numerous ridges and troughs and a lack of sediment cover in the axial part. Young magnetic lineations (anomalies 1-2A) are observed within the fracture zone wni.cn are orthogonal to the older Nazca plate lineations. The central anomaly narrows west- ward and can be observed up to 400 km seaward of the trench whereas anomaly 2A is terminated about 200 km from the trench axis. Recent SeaMARC II sonar mapping in the region shows large igneous blocks in the Trench axis to the north of MFZ but absent to the south. We believe these blocks represent young seafloor of MFZ rift/spreading center broken off from the ridges as they subduct along the Peru Trench. The MFZ rift is propagating west- ward at a rate of 115 km/Ma (25 km/Ma relative to the South American plate). Given the present rates of accretion at the East Pacific Rise and of propagation along MFZ rift, the Nazca plate will be divided into two parts in about 35 Ma.

Jan 1, 1987

This paper summarises the current status of the mining sector in Poland in terms of vertical transport system safety. Selected results of research programs conducted at the AGH-UST relating to mine hoist system safety are reviewed. The conclusions support the notion that the costs of vertical transport systems can be reduced, while at the same time maintaining the required safety and reliability levels. Novel solutions: movable fender beams HWR, linings modar« and the integrated shock absorbers PHH for conveyance guiding systems fully confirm this hypothesis.

Jan 1, 2005

By H Zhang, S Li, J Song, Z Lv

In this paper, a method for extracting and refining metallic molybdenum using low-temperature ZnCl2- NaCl-KCl molten salt was proposed. The electrochemical behaviour of molybdenum ions in ZnCl2- NaCl-KCl molten salt was investigated in detail, and pure metallic molybdenum was collected on the cathode. The reduction and diffusion processes of Mo(V) ions in ZnCl2-NaCl-KCl molten salt were determined through a series of electrochemical methods. The diffusion coefficients and nucleation modes of Mo(V) ions were also studied, and electrolysis was conducted for a prolonged period at a constant current density. The results indicated that the electrode reduction of Mo(V) ions in ZnCl2- NaCl-KCl molten salt proceeds through a three-step reaction: Mo(V) → Mo(IV) → Mo(III) → Mo at 250°C. The Mo(V) → Mo(IV) reaction was reversible and diffusion-controlled, with a Mo(V) diffusion coefficient of 6.02 × 10-6 cm2 s-1. Additionally, the nucleation mode of Mo(V) ions was instantaneous nucleation. The products electro-deposited were confirmed of metallic molybdenum with a particle size of less than 1 μm.

Aug 21, 2024

By Gilligan P

The Selwyn gold-copper operation is wholly owned and operated by the Arimco mining group. The mine is located 150 kilometres south-east of Mount Isa. The primary extraction method for the gold-copper 251 orebody is by sub level open stoping. Secondary extraction is from the mass blasting of the remaining crown and rib pillars. The final mass blast of the 251 orebody occurred in December 1993. This paper details the design and execution of that firing.

Jan 1, 1994

Magmatism is of first order significance in the extension process. Continental extension is terminated when sea-floor spreading commences, but sea-floor spreading will not commence if magmas do not begin to arrive in sufficient volumes. In the oceanic lithosphere, the rate of magma supply may determine whether sea-floor spreading takes place, or lithospheric extension as the result of normal fault arrays. In continental crust thickened as the result of previous compressional orogeny, the availability of magma may determine a completely different process. The author has examined metamorphic core complexes in a number of tectonic environments, in the North American Cordillera, in the Aegean Sea, Greece, and in the Solomon Sea, Papua and New Guinea. What these terrains have in common is a major collisional orogeny predating a major extensional event. The "roll back" of the lithospheric flexure associated with subduction can be seen as the "driving force" for extension in two of these cases. Metamorphic core complexes in these environments are characterized by domal exposures of crustal scale ductile shear zones, underneath which massive plutonic complexes have been formed. Emplacement of these plutons is associated with anatexis of the surrounding rocks. Migmatite complexes are well developed in the Aegean and Solomon Sea core complexes, and in some core complexes in the Basin and Range. Chains of core complexes can be explained as the result of basaltic and andesitic magmas derived from a linear belt of relatively hot rising asthenosphere, in a zone of attempted continental "break up". It is argued that core complexes are the results of magmas derived from relatively short lived mantle "hot spots" impingeing on extending continental crust which has been overthickened during previous compressional orogeny.

Jan 1, 1990

By Haslam C. O, Taylor S

Four historical periods of Australian lead-zinc-silver exploration and development are identified.In the first period, 1841-1900, Australia's deeply weathered surface yielded bonanza deposits. The outcrops of easily worked secondary ores, enriched in silver and lead, were discovered by prospectors with the incentive of production at times of high silver price. Districts discovered in this period still contributed, in 1982, 60 per cent of Australia's lead-zinc production, mainly from Broken Hill.The second period 1901-1944, was one of strong mine development but stagnant lead-zinc-silver exploration. Mount Isa was discovered and developed, but otherwise effort was devoted mainly to the mining of deposit extensions and to the metallurgical flotation of zinc. The deposit discovery rate was low but the discovery of Mount Isa was so significant that discoveries of this period contributed, in 1982, 30 per cent of Australia's lead-zinc production.The third period 1945-1972 was one of re-invigorated exploration.New geological and geophysical surveys, developing concepts of ore genesis, and worldwide comparisons of orebody settings improved target area selection. Evolving remote sensing methods, and rapid analytical techniques, assisted detection of lead-zinc deposits. Initiation of exploration led to discovery:1. in regions of previously unsuspected lead-zinc-silver potential (Sorby Hills, Mons Cupri, Golden Grove).2. of poorly exposed deposits in recognized mineral districts (Hilton, H.Y.C., Woodlawn, Elura, Que River).3. during active exploration for another commodity (Brown's, Woodcutters, Mary River, Beltana, Lady Loretla and Pegmont).The period saw a sustained growth in lead-zinc-silver production mainly from established operations. Mines discovered during the third period contributed, in 1982, 7 per cent of Australia's lead-zinc production.In the fourth period from 1973 to the present, exploration initiatives became fewer but resulted in continued discovery of poorly exposed deposits at Teutonic Bore, Thalanga, Benambra, Scuddles, Hellyer, and Jillawarra. Development initiatives strengthened in the period and production commenced at Woodlawn, Teutonic Bore, Que River and Elura; pre-feasibility work commenced at Scuddles, Hilton, Lady Loretta and Thalanga.

Jan 1, 1984

By Lee M. F, Guilfoyle K

A large hard rock rib pillar was recently preconditioned at Mt Charlotte mine using a novel blasting technique. The motivation for trialling this procedure was a history of past pillar failures, with associated seismicity. Design studies had shown that a new proposed pillar would be at risk of violent failure, and preconditioning was used in an attempt to reduce this risk. Preconditioning by blasting involves physically modifying a selected zone of ground in advance of mining, then forming the pillar so that it incorporates that zone of ground. The modified rock in the zone is intended to allow extra closure (yield) of the pillar in response to mining-induced stress changes. The ground modification was done by tight firing a blasthole array to fracture the rock. The blast design comprised pairs of pre-split blastholes to create a series of short cracks across the target zone, followed by main blastholes to fracture the rockmass between each pair of cracks. A monitoring program was used to establish whether or not the preconditioning was effective. It included conventional extensometers, stress change cells and closure stations, plus a seismic monitoring system. To-date, stoping is complete on one side of the pillar and has just commenced on the other. Results show significant movements within the preconditioned zone and on geological structures in the pillar, as well as lower stress in the pillar compared to an adjacent non-preconditioned site. The preconditioning technique can be applied elsewhere, provided its purpose, mechanism and side effects are understood. Benefits are likely to include more assured production, and successful pillar recovery even in high stress situations.

Jan 1, 1995

By N LaBranche

The resurgence of Silicosis and Coal Worker’s Pneumoconiosis (CWP) in coalmines has placed the spotlight back on the management of worker exposure to particulate matter across all mining sectors (Coal Workers Pneumoconiosis Select Committee, 2017). There already exists a substantial body of knowledge on particulate matter and its impacts upon human health (National Academies of Sciences, Engineering and Medicine, 2018). The contribution of silica to respiratory disease is well known. However, it is also clear that there are major gaps in our understanding. In part, those gaps relate to the contribution to adverse health effects of mineralogical constituents in the dust (LaBranche et al, 2021a). It is also becoming evident that the size and shape of the particulate matter can affect its potential impact on human health. The University of Queensland has developed a methodology for characterising respirable and inhalable dust samples using scanning electron microscopy. Multiple samples from numerous mining operations have already been analysed using the UQ methodology. The process has been successful in showing the variety of mineralogical components and particle size distributions present in various areas of the mines.

May 5, 2022