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The last decade has seen a very rapid development in TBM tunnelling. Some trends are purely technical or economical and others relate more to preferences of different interests. Power levels have more than doubled and thrust levels too. Shield machines are developed to be able to handle harder rock and the open TBMs are made more feasible for `difficult' rock. What is right and what is wrong is more a matter of opinion, but one thing is certain: TBMs now are a useful tool and no longer an experimental work-shop for the enthusiasts.This paper highlights some recent developments and indicates some probable future ones. A few features that have increased the open TBMs' ability to cope with ever harder rock and also to overcome problems with poor rock are discussed in detail, using the Atlas Copco JARVA Mk 27 -the most powerful TBM built so far - as a reference.

Jan 1, 1993

By Leahey T. A

The variability of gold mineralization in the Warrego Gold Pod is described by classical statistical techniques using sample distrib- utions and analysis of variance; and by the use of geostatistical variogram analysis to define the spatial variability and anisotropy of the mineralization. Comparison is made between declared mine production from the Nineteen Stope and a series of ore reserve estimates derived by manual, numerical and disjunctive kriging methods.

Jan 1, 1979

By Higuchi K

Intorducing the hypothesis that the cause ,òi spontaneous combustion of coal is depending un the accumulation of heat produced by its oxidation, the authors derived the equation expressing the temperature change in a heap i fine coal. To solve the equation, thermal conductivity, specific heat and rate of heat ,eneration of fine coal (-48 mesh) were measured at various temperatures in the range _'0-65¦C. The equation was solved numerically and the volume of fine coal which would ignite spontaneously was estimated as the function of ambient temperature. Using 170 Kg of fine coal, everal experiments for confirmation were conducted. At the ambient temperatures of 60¦C nd 50¦C, coal began to fire spontaneously brut 00 and 110 hours later respectively. Iii addition to this, the measured t,,rp,i,itures in the coal heap agreed with the ,aLulated ones comparatively well, If more volume of fine coal were used, experi;:ontul ;,eneration of spontaneous combustion from ...,n-, , 1-1 I'd Sill al r..

Jan 1, 1981

By Pinczewski WV, Nowak LP, Tanzil WBU, Jenkins DR, McCarthy MJ

An experimental and theoretical study has been made of the drainage behaviour of two-dimensional packed beds drained from an outlet in the sidewall of the bed in order to identify the fundamental me- chanisms involved. Under these conditions a grad- ient develops in the air-liquid interface in the direction of flow with the interface tilting towards the outlet. This results in a significant volume of liquid being retained in the packing on completion of draining when the interface first reaches the bed outlet. Residual liquid volume and the shape of the air-liquid interface as a function of time were det- ermined experimentally in a two-dimensional packed bed where the packing consisted of glass spheres ranging in size from 0.6 to 10 mm dia. and the bed was drained at superficial liquid velocities rang- ing from 0.007 to 0.32cm/s. The test liquids used were water, glycerine/water solutions and kerosene resulting in a viscosity range of 1 to 10 mPa.s and a surface tension range of 0.0243 to 0.072 N/m. Assuming laminar flow within the bed, a compu- tational model was developed to predict both the liquid residual ratio and the temporal evolution of the drainage profile within the bed. The computed results were in good agreement with the experimental data over the entire range of conditions invest- igated. the computational model was used to estimate the relative importance of the effects of changes in hearth conditions on residual slag volume for typ- ical blast furnace operating conditions. On the basis of the computed results it is concluded that coke quality is a major parameter affecting hearth drainage performance.

Jan 1, 1981

By J S. Petersen

The occurrence of coarse gold particles leading to grade complexity and sampling challenges is a common feature of many gold deposits. Poorly designed sampling protocols applied to these deposit types can lead to an excessively high fundamental sampling error. Together with other errors, the fundamental sampling error contributes to the nugget effect. Proper sample collection, preparation and assay protocols are required to minimise this error, and hence reduce the total nugget effect. Reduction of the nugget effect is a key requirement for subsequent geostatistical resource estimates to be effective. A case study from the Nalunaq gold mine in Greenland is presented, which is characterised by notable quantities of coarse gold (>30 per cent +100 ¦m gold) hosted in quartz veins. Diamond drilling provides a good measure of gross geological continuity at practical grid spacings, but is not considered to represent the mineralisation effectively. On-reef development with face and bulk sampling, together with detailed geological studies were undertaken during the resource delineation phase. This contribution describes the nature of the Nalunaq deposit, its gold particle size characteristics, how sampling and assay protocols were developed (including QA/QC issues), application of GyÆs sampling theory and its calibration, and how the data was subsequently applied to grade estimation.

Jan 1, 2005

By R Wheeler, E Stalenberg, J Lemon, M S. Crowther, D Lunney, K Ross

Gunnedah, in north-western New South Wales (NSW), including the town, the surrounding Liverpool Plains and the Pilliga forests to the west, are currently the subject of intense mining interest for coal and coal seam gas. Achieving positive outcomes for koala conservation on mined landscapes will require a sound grasp of koala ecology; and local knowledge of koala movements, tree choice and associated threats to the continued survival of koalas, particularly roadkill from increased mining infrastructure. This requires a research-oriented approach to testing ideas applicable to the long-term survival of koala populations. Our recent koala research in NSW has shown that, in 2006, Gunnedah had the largest koala population west of the Great Dividing Range, and the only population in NSW that was expanding. That prompted us to instigate a detailed study in 2008 - 2011 to determine, inter alia, whether the koalas were using trees that were planted in the 1990s to cope with rising soil salinity. Our GPS-tracking has shown that regrowth trees as young as ten years old can attract koalas. In 2009, the demise of about a quarter of the local koala population from an intense heatwave gave us a foretaste of how habitat and climate change interrelate at the landscape scale. We are now examining the optimal combinations of tree choice, and patch size and shape, for habitat restoration. This will be relevant to local coal seam gas and coal mine proposals, and ongoing mitigation actions. The Senate enquiry of September 2011 on the koala and demonstrated the intense public interest in the survival of this iconic species. Its subsequent listing for Queensland and NSW under the Commonwealth Environmental Protection and Biodiversity Conservation Act 1999 further raises its profile and obligations for management of koalas and their habitat. It will take considerable effort to manage the Liverpool Plains koala population for the next 50 years in the face of extensive land-use changes from mining, and the attendant threats from road kill, compounded by the new threat of climate change manifesting itself as an increased frequency of heatwaves and more severe droughts. This paper describes the research that underpins these conclusions, identifies some of the research approaches needed, argues for working strategically now, rather than try to patch up matters after the event, and presents a set of guides for environmental plantings. CITATION:Lunney, D, Lemon, J, Crowther, M S, Stalenberg, E, Ross, K and Wheeler, R, 2012. An ecological approach to koala conservation in a mined landscape, in Proceedings Life-of-Mine 2012 , pp 343-352 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 10, 2012

The statistical nature of the variability in detonation times of pyrotechnic delays is discussed, and how to evaluate the probability of required detonation intervals is shown. Some methods (analytical and stochastic) are given for designing blasts to ensure that any adverse effects on the variability in the delays is taken into account and minimised. Using computer models of blasts, detonation simulations can be used to check the initiation sequence for the probability of sequence reversals, indicating areas of high blast damage potential. Charge consumption rates, which relate directly to the resulting vibration levels, can be examined for their susceptibility to variation from delay variability. Models that synthesize vibration waveforms for production blasts, when taking delay variability into account, indicate the difficulty in vibration level prediction.

Jan 1, 1992

In the flotation of fine particles, problems arise which do not occur with coarse-ground pulps. For example, the presence of colloidal or near-colloid- al gangue particles gives rise to ex- cessive entrainment in the froth, with reduced grade as a consequence. If the values themselves are finely dissemi- nated, the recovery usually decreases as the particles diminish in size, so a low recovery is combined with poor grade. Sutherland and Wark (1955) referred to the complications arising from the presence of fines, indicating (p.382) that fine grinding "introduces diffi- culties that have not yet been satis- factorily overcome". At the time of writing, very little work has been done on fines flotation specifically, yet the groundwork has been well laid. The availability of better scientific instruments, together with the general advance of understanding in a wide variety of relevant research fields, has taken us a long way toward finding the reasons behind the problems as- sociated with fines, and also toward finding practical solutions. It would be useful to define what is meant by "fine" particles before going further. To some extent, the definition is somewhat elastic as far as flotation is concerned, because the density of the particles has a bearing on whether or not they act as fines. But in general we are dealing with particles less than about 20 pm in Diameter.

Jan 1, 1984

By May P. M

The role of chemical speciation in alkaline cyanide solutions is discussed by reference to recent experimental data from the authors' laboratories. It is shown that serious gaps exist in our present knowledge of the thermodynamics of cyanide complexes in solution. Nevertheless, using the available data and the JESS suite of computer programs it has been possible to develop a simplified chemical speciation model for alkaline cyanide solutions under conditions relevant to the gold extraction process. Some possible implications of the model for plant operations are Discussed.

Jan 1, 1991

The paper poses certain questions relating to mine design aspects of deep shaft pillars. It then explores these questions in relation to Western Deep Levels (South) where a sub-shaft system is to be sunk to 4 000 metres below surface to exploit two narrow tabular reefs in the down dip extension of the mine workings. After brief discussion of some broad considerations, the findings of a major rock mechanics investigation are reviewed. Some overall conclusions as well as the outcomes of separate studies of the anticipated behaviour of shaft pillars on each of the two reef horizons are outlined. The effect of this behaviour on the barrels of the shafts in the system and on the associated shaft excavations and in-pillar development is Cnnctdarcrl

Jan 1, 1986

By Moffatt G

Approval to operate Longwall No. 7 at Appin Colliery in 1979 was granted pursuant not only to the usual statutory provisions, but also that an adequate means of drainage of methane gas be incorporated. A methane drainage plant was subsequently designed and constructed some two km from the pit top at the site of the Colliery main upcast and down cast shafts. Modern plants of this nature are completely automated using programmable controllers and computers to provide control and management reporting functions. Complex mechanical systems are installed to extract the gas and in handling and storage processes. Gas utilisation plants exist which can generate power from methane. These plants are further enhanced by harnessing waste heat produced in the generation process. The installation, automation control and monitoring of these plants incorporates many facets of engineering from high voltage power supply and computer technology to complex gas handling procedures used in gas compression storage.and generation of electric power.

Jan 1, 1982

By Scott IR

In stratigraphic orebodies, estimation of footwall and hangingwall location is often of more importance than grade estimation. Contoured grade estimates often produce smeared boundaries and the use of accumulations and thicknesses as variables re-introduces the original problem: location of the point at which the estimate is to be made. The paper introduces statistical and geostatistical techniques for the solution of the problem and illustrates the techniques with a case study from Mount Isa, one of the world's largest producing silver-lead-zinc deposits. Solutions for calculating variograms in orebodies of variable dip, strike and plunge are presented together with relative variograms for individual metals, metal accumulation and orebody thickness. Optimal methods for hangingwall and footwall location are introduced and illustrated with an example. Orebody boundaries are then kriged after which individual metal grades are kriged within the estimated boundaries. The boundary estimates are compared with manually interpreted boundaries and known boundaries in mined-out areas. Grade and tonnage estimates are compared in mined-out areas.

Jan 1, 1986

Current mine ventilation systems have evolved from simple, limited energy, series or multi split layouts motivated by low suction, slow running, surface fans. Concentration of coal production from fewer working places and ventilation splits, and varying needs, hazards and challenges, however, have led to substan- tial changes. Modern ventilation systems, therefore, are more complex, sometimes more interdependent on others, more energy intensive, and are founded on the use of multiple airways and greater suction, higher speed surface ventilators and often booster fans. Intensi- fication of output has resulted also in higher gas emission rates, the wide adoption of fire- damp drainage, and sometimes in particular problems such as spontaneous firedamp emissions. Some coal mines are subject to spontaneous outbursts of coal and firedamp. These and related matters and current practices and developments are leading to discernible trends, potential advances, and further changes in Practice.

Jan 1, 1983

By Rowley M, Bradford P

Plutonic Resources Limited (formerly known as Pioneer Mineral Exploration Limited) delineated, developed and operates the Plutonic Gold Mine located 180 kms northeast of Meekatharra, Western Australia. Gold mineralisation was discovered in the Marymia greenstone belt by Great Central Mines NL (GCM) in 1988. There was no previous, recorded gold mining activity in the area. In May 1989, Plutonic Resources Limited (PRL) entered into an agreement to acquire a 51 per cent interest in the three Mining Leases containing the Plutonic deposit from GCM. Subsequently in December 1989, PRL acquired the remaining 49 per cent interest in the Mining Leases. PRL and GCM are also involved in a 51:49 regional joint venture on extensive Exploration Licences in the vicinity of the Mining Leases. Following due diligence validation, reserve delineation and testwork, a feasibility study was undertaken in conjunction with JR Engineering Services, which led to the financing and development of the project for operation in August 1990.

Jan 1, 1991

By Okabe K

Development in the theory and practice of hearth drainage is reviewed. Difficulties in the hearth drainage were re- newed during late sixties and early seventies when the size of a blast furnace and the top pressure were increased to result in the increase in tapping rate. Hearth drainage was improved first by in- creased number of tapping and then decreased tapping rate as it was predicted by theoretical studies. State of the coke bed in the hearth, e.g., 'floating' or 'sitting-on' the hearth bottom, is discussed in relation with influential factors on it and its influence on the furnace operation. The 'sitting-on' coke bed is to be aimed at for the consistent furnace working and for the lower rate of erosion of the hearth refractory. As the continuous tapping became standard prac- tice in large blast furnaces, the interest in the basic research renewed. Prospect of the further research including mathematical modelling of the hearth drainage is discussed.

Jan 1, 1981

By Stewart R, Manson RA, Haig DW, Perembo RCB, Kruman B

Since the advent of plate tectonic modelling, the Ramu-Markham valley has been thought the site of a classical island-arc/conti- nent collision zone. In this interpretation the units south of the Markham Valley are held to be island are / micrcontinental mate- rial accreted to Australia and those north of the valley are thought to represent a separate Finisterre island-arc terrane. Recent remapping by the Geological Survey of Papua New Guinea shows: (1) there is no terrane boundary along the Ramu-Markham valley (2) the Finisterre Volcanics are probably part of either a fore-arc sequence or oceanic plateau obducted onto a microcontinent/ volcanic-arc composite terrane, accreted to the continental Australian plate. A new tectonic model is proposed for northern PNG and involves: (I) Eocene to Late Oligocene subduction below a microcontinent remote from Australia to produce the Sepik are and related intrusives, the Finisterre Volcanics (fore-arc or possible oce- anic plateau), together with the Alife blueschist. (2) obduction of the Sepik arc in Late Oligocene-Early Miocene times over the advancing Australian plate. This resulted in crustal melting, some of the products of which are the Mid- dle to Late Miocene Akuna and Bismarck intrusive complexes of the Maramuni arc. (3) obduction of the Finisterre Volcanics began in Early Pliocene times and continues today. (4) post-Middle Miocene mineralisation is the result of melting after obduction of the Sepik microcontinent.

Jan 1, 1997

By Armstrong M

The highest grades of the Porgera gold deposit, Papua New Guinea, are contained in Zone 7 due to the presence of the Roamane fault, which acted as channelway of the gold-bearing fluids. Prior to the development and underground mining of this fault-controlled high-grade zone it was critical to provide grade estimates of relatively small mining units, and of the proportion of mining units above cutoff. To be applicable to Zone 7 of Porgera a grade estimation method should account for the following:1. the highly skewed and apparently lognormal distribution of the grades,2. the rapid drop off of the local mean grade and the variance as the distance to the Roamane fault increases,3. the presence of high grade pockets in the footwall, away from that fault, and4. the existence of variograms for the logs with sills parallel to the fault and without sills perpendicular to it.

Jan 1, 1990

By Mason D. O, Tuckwell K. D

Whole rock geodhemical analyses from samples of Potosi gneiss within the Willyama Supergroup have been utilised to identify geochemical trends towards Pb/Zn ore positions. Although the analyses come from disparate sources they have been incorporated in the data base only if locational, sampling, analytical, lithological and stratigraphic descriptors were reliable. These data have been statistically analysed using programmes of the GASP software package. A discriminant function has been derived which permits Potosi gneiss associated with the Pb/Zn lode horizons in the Broken Hill domain to be distinguished from Potosi gneiss in a similar stratigraphic position in the Maybell Domain. In the "near ore" position the Potosi gneiss has significantly lower mean Na2O and significantly higher mean MnO. Also mean Rb, CaO and K20 are higher and mean Sr lower. This discriminant function serves to identify areas prospective for Pb/Zn mineralisation. A second discriminant function based on MnO, Si02 and K20/Na20 gives a semi- quantitative indication of proximity to ore.

Jan 1, 1983

By Quinlan M. J, Ratcliffe J. S

Chemical kinetics is a dependent process which usually correlates the rate at which a reaction proceeds with the mechanism descriptive of the manner by which reactive particles interact. Given the latter, the object gen- erally is to find the reaction rate dependency in terms of an intensive property of the system - number of reactive particles present, and of the energetics of the system - usually temperature. Chemical kinetics depend on a dem- onstration that reaction considerations alone control the phenomenological process under study. For these rea- sons, chemical kinetics are usually involved in homogeneous gaseous systems. Even in liquid homogeneous sys- tems earliness or lateness of reactant mixing rather than chemical kinetics may be controlling. Considerations of transport phenomena are involved in heterogeneous systems and often control the observable rate:an additional problem in such systems is to apportion the rate due to mass transfer - usually a linear process - and that due to reaction which may be linear or non-linear. Experimentally, conditions are often chosen so that only one consideration controls but this becomes more difficult where solid phases are involved. Kinetic modelling involves considerations of chemical kinetics, transport phenomena, and factors attributable to the physical environment in which the process takes place. The latter two considerations may be quite different as between experiment and plant. The kinetic model may be a mathematical representation of a conceptual mech- anistic model of the reaction. Alternatively, it may be an empirical relationship resulting from, for example, some curve fitting procedure applied to experimental data. The latter approach may be necessary where the system is particularly complicated.

Jan 1, 1975

The winning and upgrading of mineral raw materials necessarily includes size reduction, which serves the liberation and production of marketable products from highly valuable and bulk materials. For crushing, the following factors can be duly accounted for depending on material type and the selection of the suitable machine: ò producing a particular size distribution, ò producing a particular grain shape, ò selective comminution, ò gentle comminution, and ò producing a size range required by a specific process and/or for a specific product.

Jan 1, 1993