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This paper will discuss specifically the performances of vibrating screens having circular motion with inclined decks and linear motion with horizontal or near horizontal decks and both related mainly to coal, metalliferous, and other granulated solids applications where screening and efficient classification is required. Some misconceptions have been applied in the past with regard to making a screen type selection using either circular throw or linear throw and therefore this paper will endeavour to clarify these misconceptions.

Jan 1, 1984

The effects of process variables such as solution chemistry, flocculent type and dosage, intensity and duration of mixing, and solids type and concentration, on the performance of flocculation/clarification/thickening processes are described. System response is evaluated in terms of the specific effects on floc settling, supernatant clarity and sediment compressibility. The implications of these results with respect to industrial practice are discussed and general guidelines for direct application to plant design and operation are suggested.

Jan 1, 1993

By C M. Hall

We report 40Ar/39Ar ages for adularia and illite from veins and wall rocks at the Waihi and Favona deposits, in the Waihi district. One sample of vein adularia from the Favona deposit yielded a plateau age of 6.04 ¦ 0.06 (la) Ma, and two samples of vein adularia from the Waihi deposit yielded plateau ages of 6.17 ¦ 0.03 and 6.17 ¦ 0.09 Ma. Two samples of wall rock adularia from the Waihi deposit yielded plateau ages of 6.07 ¦ 0.06 and 6.08 ¦ 0.03 Ma. Adularia ages overlap at the 2s level, and we do not consider them to be significantly different. Two samples of illite from wall rocks at Favona have total gas ages of 5.66 ¦ 0.04 and 5.65 ¦ 0.04 Ma, and retention ages of 6.57 ¦ 0.04 and 6.61 ¦ 0.04 Ma, whereas one sample of vein illite yielded a total gas age of 5.29 ¦ 0.17 Ma, and a retention age of 6.26 ¦ 0.19 Ma. The total gas ages of illite are minimum ages that are equivalent to conventional K/Ar analyses, whereas retention ages of illite are maximum ages. Although interpretation of the illite data is complicated, the adularia results strongly suggest that the Waihi and Favona deposits formed contemporaneously in the same fossil geothermal system at 6.0 to 6.1 Ma.

Jan 1, 2003

By D Kepert, C Simpson, D Edwards

Channel iron deposits (CID) currently supply over 40 per cent of the seaborne iron ore trade out of the Hamersley Province. The two well documented producing systems (Robe and Marillana palaeochannels) were both discovered during early reconnaissance mapping principally by BHP Billiton (BHPB) and Geological Survey of Western Australia (GSWA) during the mid 1950s to early 1960s. Both crop out extensively over the majority of their length. Hot on the heels of Fortescue Metals Group 2004 - 2005 discovery of approximately 2.6 billion tonnes (Bt) of undercover iron ore mineralisation in the Chichester Range, the Fortescue Exploration Department turned its attention elsewhere throughout the Hamersley Province. Reappraisal and analysis of publicly available data and ground truthing of developing models led to the recognition of the Solomon palaeochannel system. Subsequent exploration defined a world-class Resource of some 1.9 Bt of iron ore mineralisation of which the great majority is buried CID. Apart from the Marillana CID system, the Solomon region is the only major CID with significant tonnes of sub two per cent alumina CID with over 500 Mt delineated to date. Exploration has also outlined significant supergene bedded and detrital iron ore mineralisation. Ongoing drilling is expected to increase the resource base both in terms of tonnes and confidence. This paper outlines the principal contributing factors which led to the discovery of the Solomon CID and compares its geology with the Robe and Marillana palaeochannel systems.

Jan 1, 2009

THIS instrument, depends on the principle that, over a short period, the surfaee of a porous substance from which a liquid is evaporating receives the same amount of heat by conduction, convection, and radiation as it loses in the latent heat of the evaporating liquid. If, then, the amount of heat being received by a surface can be measured, the rate of evaporation can also be obtained. The Kata thermometer is also based on this principle differently applied.The instrument, as shown in Fig. 1, consists essentially of a thermometer with a sliding which is divided by three pointers into two equal parts which may be spaced so as to cover a distance of, for example, 5° of the thermometer scale. The instrument is calibrated so that the amount of heat required per unit area of the bulb to raise the menissus is known. The method of using the instrument is as follows:The slide is first set so that thc central pointer is at the temperature of the evaporating surface.The thermometer is cooled by any convenient means so that the meniscus is several below the lowest pointer. The thermometer is then placed near the evaporating surface, when the Ineniscus begins to rise and the time taken for it to rise from the lowest to the top pointer is measured. From this and the calibration results the amount of heat retained per unit area of the bulb at the mean temperature...

Jan 1, 1928

By Bulters J, Sheppard I

Two blasthole density logging programmes have been conducted on the Mt Whaleback iron ore mine to evaluate the use of this type of logging as an aid to blast pattern design. The first programme also involved the setting up of a Density Test facility with which to calibrate the density probe. The programmes indicated that about 22-23 blastholes can be consistently logged per day at a cost of $1.30 per metre. Even though this is only half the rate required to log the average number of blastholes drilled daily on Mt Whaleback, testwork indicated that no significant loss of accuracy results if only half the holes in a pattern are logged. The major results of the programmes were: 1. The density range for black pyritic Shale is 2.2-2,9 g/cc. 2. The density range for soft to medium hard BIF is 2.1-3.0 g/cc. 3. The density range for hard BIF is 3.0-3.6 g/cc. 4. The front row blastholes show consistently lower densities than the main body holes due to blast damage. 5. A low density zone extending to a maximum depth of 6 m occurs at the top of most blastholes and results from blast damage from the bench above. These density results have been used to implement savings in drilling and blasting via pattern expansion and charge optimisation of blastholes. Eight ore

Jan 1, 1986

By P Krauss, S Harpalani

Methane emitted from underground coal mines, along with ventilation air and known as ventilation air methane (VAM), constitutes the largest component of coal mine methane (CMM) emissions. Atmospheric methane, on the other hand, is a potent greenhouse gas with a significant adverse impact on the atmosphere. This has led to the development of various technological alternatives for its use as an energy fuel. Techniques involving oxidation of VAM, usually consisting of very low concentrations of methane, have been validated in the past. Prominent among these technologies are the thermal and catalytic flow reversal reactors, ancillary fuel technologies, lean fuel gas turbines, and concentrators and gasifiers. However, the efficiency of any VAM utilisation technique depends on the amount and concentration of methane in the ventilation exhaust air. Therefore, quantification of VAM emission from a coal mine is the first step towards identifying the most suitable technology for its utilisation for energy production. This paper presents an evaluation of the efficacy of VAM as an energy source. It provides details of a case study aimed at developing a technique to accurately quantify VAM emission from a coal mine. It further discusses the various VAM utilisation techniques available, and presents an economic evaluation of the alternatives. Based on the findings of the study, the most feasible method for VAM utilisation is identified for the mine. The paper summarises the procedure for quantifying VAM emissions and selecting the most suitable utilisation technique.

Jan 1, 2005

The basic principles of mineral valuation were recognised and propounded at the beginning of this century and have remained virtually unchanged since then. Valuation is seen as a two part process commencing with a technical examination of the mineral property followed by a manipulation of the results of the technical examination in order to determine the monetary value of the project. A thorough and competent technical examination was seen then and remains now as the essential but not sufficient foundation for reliable valuation. All authors stressed the need to maintain the integrity of the data base and to ensure adequate coverage of all relevant aspects. The monetary valuation process through most of the first half of this century was mainly based on the Hoskold two rate method, derived from the formulae for valuing annuities but modified to provide explicitly for recovery of capital. Though the basic principles of valuation have not changed significantly, the means of implementing the components of the technical examination, the styles of deposits being evaluated and the mechanisms of monetary valuation have changed dramatically. Despite all the technological improvements, however, mineral valuations are still as apt to vary from realised performance as at any time in the past. As well, mineral property valuations are now being extended to cover all assets of potential value, including valuation of exploration tenements with or without identified resources. Valuation of exploration tenements will continue to be one of the most difficult and contentious of valuation tasks.

Jan 1, 1994

By C Aldrich

In this paper, the use of topology preserving projections (Sammon maps) and neural networks are considered as a basis for the construction of multivariate statistical process control charts for a semi-autogenous grinding circuit on a gold plant. Comminution circuits are often operated in a quasi-steady state mode, where the mills tend to move rapidly from one state to another. This makes them difficult to monitor by conventional means designed for continuous steady state processes. As a first step, process data reflecting normal operating conditions are mapped with SammonÆs algorithm. Only one feature is extracted at a time and each mapping is captured by a neural network model to allow online application. Reverse neural network models are used to reconstruct the data prior to the extraction of subsequent features from the data residuals. The ensemble of neural network models can then be used for both fault detection and identification. The approach compared favourable with both linear and non-linear principal component models. It was able to detect two simulated fault conditions both with a reliability of 100 per cent, as opposed to 57.8 per cent and 95.2 per cent detected by an approach based on the use of linear principal component analysis and 84.1 per cent and 98.0 per cent detected by an approach based on non-linear principal components extracted with auto-associative neural networks.

Jan 1, 2007

The Mount Lyell Company's concentrating mill is situated about a quarter of a mile westward of the portal of the North Lyell tunnel, which serves the North Lyell, Royal Tharsis and Crown Lyell mines, being on the 1100-ft. level of the first named. The Comstock mine is connected with the tram system at this level by five and a half miles of steam tramway, two-foot gauge being standard throughout.The plant is well placed with regard to all essential services and has an excellent water-supply from a series of three dams on the West Queen river.MILLING ORESThe mill feed is a mixture of the outputs from the foUr mines mentioned, each of which has its characteristic ore, but, generally speaking, about half of the ore consists of siliceous schists and the other half of hard grey quartzite. The schisty ores are easy to crush, but, on grinding, while the schist slimes readily, the quartz granules are hard, resulting in the handling of heavy loads on the secondary classifiers. The quartzite ores are both hard to crush and difficultto grind.The principal sulphide materials are bornite, chalcopyrite, and pyrite, chalcopyrite being the main copper-bearing mineral.The crystallization is coarse in the schisty ores, but it has been shown that even the 200 mesh (Tyler) material contains included sulphide particles. At the present time the sizing of the final tailing averages 80% through 200 mesh.

Jan 1, 1932

An image analysis system has been built which automatically digitizes camera input of rock fragments, analyses the digitised data to determine the sizes and shapes of the rock fragments, and outputs the analysed data to a printer in the form of a histogram or a scatter chart. The high speed of such a system allows for direct collection of data from material thrown into the air by blasting, material travelling on a conveyor belt, and material free-falling on to a stock-pile or into or out of a rock-crusher. Data on the blasted, un-crushed material provides information on changes in the lithology and structure of the rock face as it is quarried or mined: flatter fragments may represent approach to a brittle, unstable shear zone, or a change from sandstone to shale; so that the informa- tion reflects the effect on the sizes and shapes of the fragments by the blasting process and/or by the rock structure. The size and shape distributions of rock fragments produced during blasting and during processing may now be continuously monitored. Such detailed analysis of the results of fragmentation is labour-intensive and expensive when the size and shape distributions are obtained manually, but is cheap and efficient when using this image analysis system. Such a system will enable the results of blasting, quarrying, mining and crushing to be cheaply analysed and correlated with current and changing indus- trial practice so leading the way to increased productivity.

Jan 1, 1988

By Rabie A. S, Fouad K. M, Ammar A. A

The existence of Gabal El Kahfa ring complex, located in the Eastern Desert of Egypt, has been ascertained from aeromagnetic and aeroradiometric survey data as well as by aerial photography. Two maps for -the net aerial radiometric measurements reduced to ground level and aerial magnetic data corrected for the regional normal gradient of the earth's magnetic field have been constructed. The aeroradioactivity data have been interpreted geologically and analyzed statistically to outline various radiometric units and compute their charac- teristic statistics. The ring complex showed a circular radiometric feature and yielded a radiometric mean background and a standard deviation of 6.48 and 0.89 pR/h respectively. Besides, the observations showed a normal distribution. The aeromagnetic data have been reduced to the north magnetic pole, then filtered to produce the regional-and residual-component maps. Statistical trend analysis was conducted for the tectonic linea- ments resulting from the three magnetic maps, to define the structural framework of the area under study. This statistical study proved the exis- tence of trends in the east-west, northwest-south- east, northeast-southwest and north-south directions. The ring complex is characterized by a circular magnetic feature, whose average relief is 2150 nT. It is included within a high east-west trending magnetic zone. The latter represents a deep-seated uplift or anticline which is bordered from all sides by some faults of different trends.

Jan 1, 1988

By C Philander

The West Coast of South Africa is well known for its placer gem quality diamond deposits and also associated with these hosts of Cenozoic unconsolidated marine and aeolian sand and gravel are significant concentrations of heavy minerals. Exploration for economic concentrations of zircon, ilmenite and rutile along the coast started in the mid-1980s. This resulted in the discovery of an inferred 1.6 billion tonne resource with a grade of ten per cent total heavy minerals (THM), which developed into the Namakwa Sands Mine, a world-class producer of heavy minerals. Several other resources, including satellite deposits proximal and distal to the mine area, extensive diamond mine dumps and present day beach placers, demonstrate the vast heavy mineral potential along the West Coast. The favourable gangue to economic mineral ratio, a higher zircon content compared to other similar deposits, relatively lower U+TH content of zircon, low slimes content and effectively pristine low chromium-manganese ilmenite of these deposits, render them attractive exploration targets. Negative factors that will affect conventional mineral beneficiation and liberation include secondary mineral coatings and the regional coastal development of several layers of superimposed duricrust. The economically attractive heavy mineral assemblage along the West Coast is the result of erosion of the proximal, gneissic Namaqualand Metamorphic Province and mature Table Mountain Group sandstone, concentration by marine and aeolian processes and preservation under arid climatological conditions over a period of more than 100 Ma.

Jan 1, 2008

Single station group velocities of fundamental made Rayleigh waves over the period range 15-100 s are carguted for five provincial profiles of the West Pacific. Based on recordings of earthquakes around the West Pacific by the W~ (World Wide Standard Seismic Network) stations AFI (Afianalu), HNR (Honiara), WEL (Wellington), PAR (Raratonga) and RAB (Rabaul). The inversion of the derived dispersion curves for average shear velocity-depth structure of the crust, LID and LVL shows that (i) the over-all structure beneath the profile 'westernSamoa-Micronesia-Mariana' is in between that of regions 3 and 4 of Pacific Ocean (Yu and Mitchell, 1979), except that the velocity is slightly lower, (ii) the uppermost mantle beneath the 'Vitiaz Trench' profile between AFI and HNR is similar to that of region 2 of the Pacific - in other words, thin LID and thick LVL; (iii) the structure beneath the ' Ibnga-Keradec Ridge' profile has a thick crust with thick sediments, and LID-LVL velocity and thickness are similar to region 3 of the Pacific; (iv) beneath the profiles ' Tonga/ Kermadec Trench events-RAR station' the structure is intermediate between regions 3 and 4 of the Pacific Crean; (v) from decomposition of the 'Solomon-meriana' profile, the structure beneath the Cntong Java Plateau has a thick crust with thick sediments and the uppermost mantle is similar to that of region 3 of the Pacific clean.

Jan 1, 1990

By Milner SC

Four quartz latite rheoignimbrite units (units I to IV) mapped in the Goboboseb Mountains have been traced to their eruptive source, the Messum intrusive complex; this is a complex multistage ring structure (18 km diameter) with well defined gabbroic, monzonitic, and syenitic intrusive phases, and a central ring zone containing mixed rhyolitic to latitic agglomerates. Three of the four quartz latite units are correlated with the upper and lower (2 units) Springbok quartz latites outcropping some 90-130 km north of McIsum. This implies minimum volumes of 300-500 km for wits I and III (Lower Springbok) and 2200-2600 km for unit IV (Upper Springbok). This latter unit is still ti 300 m thick at its outcrop limit, some 130 km from Messum. Each of the four units represents single cooling units. Lithologically, each can be divided into three zones: A basal, dark grey to black flinty or glassy zone, often with highly attenuated fiamme (ressembling flow banding); a central massive and strongly recrystallised zone; and an upper variable zone which exhibit breccias, contorted flow banding, and amygdaloidal to pumiceous clasts. Their overall characteristics tend to be intermediate between ash flows and lava flows. The rheoignimbrites are interpreted as the oproducts of dense, high temperature (950¦-1100 C) ash flows which underwent rheomorphism and lava-like flow prior to their final cooling.These large scale eruptions are related to the initial rifting of Africa and S. America, possiby in response to a major hot spot.

Jan 1, 1990

By S M. Aminossadati, C M. Stewart, M S. Kizil

Mine ventilation models are now an accepted component of most mine management systems. However, modern ventilation models also represent a highly structured spatial data source, defining underground pathways and connections across a mine. This creates opportunities to extend the use of network models beyond ventilation design, by using critical path algorithms to find pathways such as minimum distance or minimum time.This paper explores the use of ventilation network models to automatically analyse and calculate potential emergency escape routes. A variation of Dijkstra’s algorithm is used to predict complex pathways between any two points across a model, representing an escape route from an emergency area (such as a fire) to a safe location (such as the surface or a refuge station). Weighting can be assigned to paths to represent potential travel speed, obstructions or preferred routes. Finally, emergency considerations such as smoke or gas in some parts of the mine can then be incorporated into the pathways to force the algorithm to avoid dangerous routes and specify safer pathways. Ventsim is used to visually show example results.Emergency egress pathway prediction using ventilation network models can provide an efficient way to quickly predict the quickest or most efficient escape routes for emergencies or planning purposes.CITATION:Stewart, C M, Aminossadati, S M and Kizil, M S, 2017. Emergency egress pathway prediction using ventilation models, in Proceedings Australian Mine Vent Conference 2017, pp 57–62 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017

By Alexander RB, Hollis AJ

The magnitude of the payloads carried by mine haul trucks can have a strong influence on the mine production rates and costs. Consequently control of truck payloads is highly desirable, but in many mines the unavailability of means for measuring payloads reliably, accurately and easily has resulted in a low level of control over truck payloads. Consideration is given to two techniques which are applicable to the measurement of payloads carried by mine haul trucks, namely truck weighing and direct measurement of payloads with truck based systems. Accuracy assessments for two types of truck weighing platforms and two prototype truck based direct payload measurement systems are provided. Results show that weighing platforms based on hydraulic components have proved inadequate, while strain gauge type weighing platforms can estimate payloads to within 2% of true payload when installed, maintained and used correctly. The assessment of the two prototype truck based direct payload measurement systems shows that a high proportion of payloads were estimated to within 5% of the payloads derived from accurate weighing platforms and that these systems appear to have the potential to provide convenient and accurate measurement of payloads. This should enable payloads to be much better controlled than has been possible to date. Predictions of the effect of payloads on production rates and some components of truck haulage costs are possible and some typical results are presented. Accurate prediction of the effect of payloads are not yet possible for some major components of truck haulage costs.

Jan 1, 1986

By Carter J. P

A two year study into the effects of coal mining induced subsidence on cliff lines was undertaken by the Department of Mineral Resources with the support of a grant under the National Energy Research, Development and Demonstration Program. A new monitoring technique, using an Electronic Distance Meter and acrylic reflectors attached to the cliffs, provided safety for the surveyors and extensive and accurate three dimensional displacement data on the movement of the cliffs as they were being undermined. The study report included many graphs showing the measured vertical and horizontal displacements, differential subsidence, tilts and strains and included analysis of these movements with various parameters, such as, seam thickness, depth of cover and distances between the reflectors, longwall face and the edge of the chain pillar. Some of these graphs are presented in this paper and could be used, with caution, to predict subsidence movements around other cliff lines, after allowing for differences in geology and mining layout. A mechanism is suggested as an explanation for the observed high horizontal movements around the cliff lines. Sixteen percent of the overall lengths of cliffs that were undermined during the monitoring study fell and the contributions of various factors that appeared to influence the cliff falls are discussed. It is concluded that no single factor dominated as the major cause of the cliff falls and, often, many factors combined to cause cliff face instability.

Jan 1, 1992

Over the past 15 years many world-class gold discoveries have been made in the region. Some deposits, such as Lihir and Porgera in P.N.G., have a contained gold resource that places them among the top dozen deposits ever found on a worldwide basis. Can we see any pattern to these discoveries, or are they the result of good luck or chance by geologists and prospectors who struck it rich? Whilst such discoveries were a feature of the gold rushes of the 1850s and the 1900s, the present boom is now scientifically based. This paper develops an argument that long-tent, multi-disciplinary exploration by experienced geoscience teams underlie the successes achieved. Dis- coveries nearly always reflect a combination of skills, drawn from the areas of geology, geochemistry, geophysics and remote sensing, and a team approach. They do not represent the chance finds of a prospector's pick or such as the Norseman discovery where the gold reef was first noted by the prospector when his horse fell over the outcrop. The following deposits provide major examples of exploration successes within the Australian-Pacific region, it is not an exhaustive list and I have noted other significant producers at the end of this paper. For the Australian mines listed and based on our estimates for 1990 gold production, they represent about 20 per cent of the Australian production total.

Jan 1, 1991

By Wooller R

The 3-D regular block model used for long term mine planning at Hamersley Iron did not fulfil the requirements for short term mine planning in terms of accurate representation of geological structures, contacts and boundaries in the orebodies. A computer model, based on zone plans, is being created as a single orebody model for all phases of mine planning. The zone plan is the primary interface between the geologists and mining engineers. It is essentially a bench plan at mid-bench height showing geological structure, material type boundaries, the grade and physical characteristics of ore blocks. The method allows for the dilution of ore zones by waste material. The stratiform nature of the orebodies allows zones of varying grade to be readily delineated on the plans. The Zone Plan Model (ZPM) is the interface between geological and mine planning computer systems. It is the basis of all mine planning with applications including long and short term mine plans, reconciliations, general ore reserve estimations, pit design and general model enquiries. The system was designed to be user driven. The user has complete control at all times as all computer generated data are fed back to the user who may then elect to override the computer. Various controls were built into the system to ensure model validity and integrity. The system has proved to be invaluable as a tool for users with little or no computing experience.

Jan 1, 1986