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By Yu A. B

An experimental study of the packing of a coal heap has been carried out. The bulk density of a coal heap is considered as a function of a number of variables, viz flow rate, conveyor belt speed, the height of the disengagement point of the conveyor belt, coal particle density, moisture content, the size of the heap and coal particle size distribution. The effects of the dimensionless numbers resulting from dimensional analysis on the packing density of a coal heap have been experimentally examined and analysed. Based on the experimental results, equations have been formulated for the estimation of the bulk density of a coal stockpile. The validity of these equations are checked by comparing the predictions with measurements of real industrial Stockpiles.

Jan 1, 1991

By M Zoorabadi

Overcoring is a common technique to measure in situ rock stress using the concept of stress relief. The strains measured during overcoring are used to calculate the stress tensor assuming continuous, homogeneous, isotropic and linear elastic behaviour. This approach does not recognise any effect of the thickness of the rock annulus produced during overcoring instead assuming that the stresses are entirely a function of the difference in strain between the start of the overcoring and the end with no regard to the transient strains produced. Three-dimensional numerical modelling was used to simulate the overcoring process and investigate the impact of core diameter on the transient stresses and strains during overcoring. This study showed that in thicker core, maximum transient axial stresses and strains occur when the drill bit approaches the measuring point and greater tensile axial stresses were produced when the annulus was thinner. CITATION:Zoorabadi, M, 2018. Numerical study of annulus thickness on overcoring stress measurements, in Proceedings The Fourth Australasian Ground Control in Mining Conference (AusRock), pp 274–278 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 30, 2018

By Keyte SG

Gravity methods of recovering alluvial gold are not very efficient at particle sizes below about 0.1mm. Whereas such gold may not have been economic to recover in the past, the same may not be true today. Centrifugal concentrators, like the Knudsen and Knelson bowls, are showing promise after an inauspicious start, at least in New Zealand. The large proportion of heavy mineral in many auriferous beach sands and the natural hydrophobicity of fine gold should make flotation an attractive contender for its recovery. The conventional mechanical flotation cell is effective, but roughing, scavenging and cleaning are necessary to achieve both high recovery and low mass yield. More problematic is the difficulty of maintaining coarse and dense sands in suspension. The air sparged hydrocyclone is effective at recovering fine gold from a fine Colarado River sand, but is not effective for the coarse and dense beach sands of New Zealand. The flotation column shows much promise for these sands, when recoveries of over 80% and mass yields of less than 1% can be achieved in a single pass. The froth separator of the USSR and flash flotation could also be worthy contenders. It is felt that flotation could be limited to naturally and artificially de-slimed concentrates.

Jan 1, 1990

By Durucan S

Uncertainty due to spatial and temporal variability of different pollutants found in soil, water and air is an important issue in the modelling of environmental impacts. Recognition of spatial environmental patterns is relatively straightforward to achieve by applying most of the well-known artificial neural networks or adopting a stochastic approach. However, it is the temporal component of the environmental variables that makes modelling of the environmental pollutants particularly complicated and challenging. This paper presents the results of a case study investigating the artificial neural network performance when modelling the spatio-temporal behaviour of environmental pollutants. The test case involved the modelling and prediction of the distribution of water quality indicators along a river from the point of discharge of treated mine effluents. The behaviour of river water quality indicators is rather complex and shows a lot of fluctuations due to a number of hydrochemical, hydrobiological and hydrodynamic factors. Results obtained in this study indicate that artificial neural networks provide a very powerful and robust method for simultaneous modelling of spatio-temporal behaviour of environmental pollutants.

Jan 1, 1995

A nuclear technique utilising the gamma-ray resonance scattering process is used at Isa Mine for the determination of copper in drill core and bulk mineral samples. The Copper Bulk Analyser (CBA) provides quick and accurate non-destructive copper analysis of drill core at costs two to three times cheaper than conventional chemical techniques.The almost immediate availability of sample results enhances the efficiency of the mine geologist in the duties of grade control, design of diamond drilling programmes, and input to planning. The unit has proven to be a reliable and accurate production tool requiring a minimum of technical support.

Jan 1, 1990

By Sheer T. J

The increasing demand for underground cooling in South African gold mines has resulted in various cooling methods being con- sidered, including the use of ice. Two main areas in connection with ice cooling systems are being investigated. The first concerns the efficient and cost effective production of ice on a larger scale than previously required for any other application. The second con- cerns the transportation of ice in pipes from surface ice-making machines to underground melting sites.

Jan 1, 1988

By Prince R. G H, Guerney P. J, Frew J. A, Vanderkruk C. R, Wanigasekara-Mohoti D. K

This computer-aided design system for mineral processing flowsheets which are based on froth flotation, size reduction and classification combines an expert system for generating flowsheet structures with numerical models for the physical processes and the economics. Design decisions, such as specification, size and placing of process units and the destination of recycle streams, are based on clear technical and economic criteria. These decisions are controlled by user-set parameters, which allow the incorporation of industry experience and preferences and the generation of sets of good designs, from which choices may be made by further criteria, such as controllability. Liberation is now fully modelled and the early results from this extension continue to suggest potential substantial increases in added value over conventional approaches.

Jan 1, 1997

By P D. Williams

The Phoenix mine is one of NewmontÆs open-pit operations located in Nevada. Mining started in 2005, with the mine producing gold, copper and silver. The mine life is about 20 years. The gold grade estimation uses the Newmont in-house indicator kriging approach to handle the high variability in drill hole composite grades and support mining selectivity. Each block contains up to 200 subblocks with different gold grades. A flotation mill is designed to process oxide and sulfide ores, recovering gold, copper, and silver. An additional copper leach process is currently under study to process low gold and high copper oxide material with low copper recovery in the mill. The metallurgical recoveries and processing costs are dependent on many variables including rock formation, metallurgical domain, cyanide soluble copper and sulfide contents. This paper describes the Newmont in-house indicator kriging procedures and the revenue based mine planning software system implemented at Phoenix mine to address the complexity resulting from multi-process, multi-metal and indicator kriging model.

Jan 1, 2007

A new gold cyanidation assay technique has been proven for a range of ores, where it has demonstrated benefits of being: ò Accurate (reduces the typical range of assay scatter almost three-fold, and avoids common fire assay interferences). ò Fast (under one hour, providing a quantum shift in space requirement and equipment utilisation each bottle roll can provide over 15 determinations per day). ò Simple (suitable for field application, no high skill or experience requirements). ò Profitable (reduced drilling, drilling time, ore misclassification and/or double handling after mining). ò Cheap (far lower cost than Fire or Aqua Regia Assays, ie LeachWELLTM costs around 10ó for a 20 g sample at 50 per cent solids, proportionately greater for larger samples eg $1 for 200 g samples which address most nugget effect problems). ò Relevant (distinguishes economic. ie cyanide-extractable gold, the only unequivocal value to use for true resource definition, mine planning and grade control). ò Robust (rough bucket chemistry of samplers does not seriously affect results). A new development is the provision of LeachWELLTM CAS, a solution, which also contains optimum cyanide and stabiliser concentrations; and offers greater: ò Safety (the dilute cyanide solutions are stabilised to avoid generating toxic HCN vapours; and present no cyanide dust or flying chips to deal with). ò Ease (a single squirt dispenses precise quantities of the entire reagent suite, avoiding multiple weighings). ò Reduction in total reagent costs. An inter-laboratory comparison on nine ore types, using two assay techniques (Fire Assay and Aqua Regia) involving 45 laboratories, has demonstrated that LeachWELLTM 60X assays for the samples tested, were equally or more reliable than typical Fire or Aqua Regia Assays. There is particularly great benefit in applying LeachWELLTM 60X assays to richer ores in comparison to Aqua Regia assays, which appear to be prone to very significant underassaying depending on individual analyst skills, and which often suffer greater nugget effects. The major impacts for heap leaching are that: ò Using the LeachWELLTM assay technique for grade control, ore of marginal grade is not accidentally discarded to waste or visa versa due to the scatter of assay data inherent in typical small charge (25 g) fire assays. ò LeachWELLTM assays very importantly report only that gold which will be recoverable in the heap, viz that which is liberated - an important factor where the coarse crush often leaves ten per cent of gold unliberated. These impacts are of particular importance for many ores (ie most of those recovered from open pit operations and at the margins of rich ore subject to slurry processing) subjected to heap leaching as the oxide zones often present major problems of nugget effects as well as mineralisation that cannot be accurately assigned through interpretation of clear structural controls.

Jan 1, 1994

By Bluck R. G

The Murray Basin is known to contain major deposits of heavy mineral sands and intensive exploration for new deposits is being conducted in Victoria, South Australia and New South Wales. The western Basin was well served in the Pliocene and Early Pleistocene by a variety of appropriate sediment sources, and potential coastal traps. Immature, fluvially-sourced sediments forming the Pliocene coastal complex of the Marmon-Jabuk Range in South Australia are part of a marginal marine assemblage containing a suite of economically important heavy minerals that include ihnenite, zircon, rutile and tourmaline. From a consideration of Pliocene palaeogeography and coastal dynamics, specific targets where concentrating processes are likely to have operated are identified in the South Australian portion of the Murray Basin. Such palaeo-environments include the down-drift, littoral zone of discrete foredunes or coastal barriers, the source area for transgressive dune complexes, tombolo facies, and intertidal shoals and sandbanks. Similar coastal processes are recognised for a preserved Early Pleistocene barrier complex.

Jan 1, 1990

By M Salu, G J. Kay

"As underground mines increasingly face the challenge of maximising production without losingfocus on safety excellence, the ability to predict the eff ectiveness of mine seals and stoppings andthe identifi cation of defects plays an increasingly important role in mine ventilation management.While technologies for sample testing installed seals provides signifi cant assurance, the difficulty of conducting tests in operational environments, combined with the production impact of destructive testing procedures, has led to the development of a new method for non-destructively testing ventilation control devices (VCDs). This paper addresses the challenges of in situ testing and reviews the approaches previously employed to verify the quality of VCD installations. It then describes a new testing methodology jointly developed by Whitfield Minerals PTY Ltd and Parsons Brinckerhoff (PB) and the range of tests that have been carried out in the laboratory, above ground, at trial underground sites and in active coal mine operations. Although this is a new approach to testing underground VCDs, the method employs recognised testing equipment in a new application. The aim of the new non-destructive technology is to not only verify the thicknessand therefore overpressure rating compliance, of new VCDs, but to allow mine operations t oidentify and locate defects in installed VCDs without causing damage to the material structure.Currently it is difficult, time-consuming and costly to carry out physical sampling and testing ofevery VCD. Therefore, a reliable and accurate means of non-destructively testing concrete andplaster seals in situ will provide substantial operational and safety benefi ts to the underground coal mining industry."

Jun 1, 2012

Gold and copper mineralization in the Parkes area is hosted by a meridional sequence of Late Ordovician to Early Silurian igneous and sedimentary rocks on the central northern edge of the exposed Lachlan Fold Belt. The mineralized area straddles two zones separated in part by the Parkes Thrust and exhibiting different styles of deformation and mineralization (Figure 1). The western zone is characterized by gently folded rocks, with shallow dips and weak to non-existent axial plane cleavage. Faulting is restricted to directions oblique to bedding. Numerous occurrences of minor copper mineralization are known, but of recent national importance is the discovery of the Coradgery- Goonumbla porphyry copper-gold deposits by Geopeko Ltd. A resource in excess of 250 million tonnes has been delineated (Jones, 1985), and this represents the first porphyry deposit of sufficient grade and tonnage to be potentially mineable in New South Wales. The eastern zone is much more strongly deformed. Folding is tight with strongly developed axial plane cleavage. Faulting is abundant both parallel and oblique to bedding. Quartz veining is also abundant, and a narrow belt of gold mineralization adjacent to the Parkes Thrust stretches from Forbes in the south, through Parkes and Peak Hill, to Tomingley in the north. Over 31 tonnes of gold have been produced from this gold belt, mostly before 1914, and now three deposits show good potential for redevelopment - Peak Hill, and the London-Victoria and Lachlan lines of lode.

Jan 1, 1987

By Golubkov OL, Fedotov PB, Shkylar FR

One of the fundamental parameters of the race- way is its extent (a{ o), which has a significant effect on the distribution of gas and material flows in the lower region of the furnace. pp The known relationships for determination of aC o in most cases link the length of the raceway with the parameters of the blast, while the para- meters of the coke layer, in which the raceway is formed, are either ignored or else expressed in terms which are difficult to determine experimen- tally. Furthermore, the coke combustion propert- ies are not always taken into account in current blast furnace operating practice with combined blast. A complex dimensionless parameter, which re- flects the properties of the interacting media, is the ratio of the kinetic energy of the hot, com- bined gas stream to the potential energy of the coke flow, burning at the tuyere in a gas of known composition. Statistical processing of experimental data on the extent of the raceway zone, obtained from literature and our own work on operational furnac- es, has led to a working formula of the following Form:

Jan 1, 1981

By Ren T. X, Jozefowicz R

In many branches of engineering, there has to be an understanding of the motion of fluids in order to solve problems. Many safety and health problems in the mining industry are typical examples that involve the understanding and analysis of fluid flow, such as explosions, the spread of fires, dispersion of gas and dust, and ventilation patterns. Computational Fluid Dynamics (CFD) is concerned with the use of computers to produce information about the ways in which fluids flow in given situations. Until recently CFD has been widely applied to a variety of industrial sectors and increasingly to problems in the health and safety areas. With the arrival of more powerful computers and CFD packages, CFD techniques are no longer practised solely in a research environment, but can be used by engineers in many industrial fields. This paper introduces the basic concepts and general procedures involved in the use of CFD technology. A comparison is given as a guide to the major features of a number of widely used commercial CFD codes. Areas of potential CFD applications are identified in a range of safety and health problems in mining industry. An example is presented to illustrate the use of this technology. It is believed that the exploitation of these areas using CFD approach will contribute significantly to the solution of today's many mine health and safety problems.

Jan 1, 1995

A comparison is made between bord and pillar and longwall coal mining. Longwall mining presents a challenge to raise the level of management and engineering practice. To maintain a competitive position in the world export market, the Australian coal mining industry must continue to use and develop the most advanced, cost benefiting, safe mining systems.

Jan 1, 1987

Underground mine ventilation is now com monly simulated on a digital computer. Such a programme, incorporating natural ventilation has been modified by others to account for methane emission and elevated local tempera- tures. At Wollongong University, the pro- gramme was further developed and extensive interactive graphics incorporated such that any view of the three dimensional mine could be viewed, and superimposed upon that view are areas where a nominated parameter has exceeded a particular value - generally at a nominated time after a particular event and usually a fire/explosion of one type or another. A further programme was developed such that up to 20 'times' could be examined at a particu- lar location after say, a fuel rich fire at some other place in the mine. The output from this programme includes a plot of methane 1, smoke 1, temperature, pressure and air flow versus time - a most useful graphic to observe the limits of safe attendance in a particular Airway.

Jan 1, 1983

By S S. Kanchibotla, S Morrell

In recent years there has been a growing recognition of the impact that mining practices have on the efficiency of mineral processing operations. Head grade, dilution, particle size distribution and their variability are known to have a significant effect on the throughput and recovery achieved in mineral processing plants. Improved process monitoring and modelling have provided the opportunity to identify and quantify some of these impacts and to define very significant incentives to optimise the overall operation from the mining face through subsequent comminution and processing. The Julius Kruttschnitt Mineral Research Centre has been undertaking research to optimise æMine to MillÆ performance through a major AMIRA research project and through individual research contracts with mining companies. This work has resulted in a broad range of field and laboratory experience in terms of both the challenges and the opportunities encountered when tailoring blasting operations to suit the overall æMine to MillÆ production chain. This paper describes the objectives of æMine to MillÆ blasting to optimise the system of rock breakage involved in the blasting, crushing and SAG milling of hard, brittle ores. The design of such blasts falls outside the conventional envelope of experience for most engineers and requires the consideration of some critical factors if the objectives of such blast are to be met and some of the potential problems are to be avoided. Experience to-date has also found that the quality of implementation is critical to the success of æMine to MillÆ blasts.

Jan 1, 1999

(Quality can be defined as that which is acceptable to the market and can be supplied with a predictable degree of uniformity and dependability at a low cost. The market for any mining product is downstream processing, whether it be an alumina refinery, a gold processing plant or a flotation plant. The cost of that downstream process is partly dependent on uniformity of its feed material both in physical and chemical terms. With more operations adopting procedures which require quality assurances in line with International Standards, from their raw material suppliers, miners must look to their grade control processes to provide uniformity and predicability.This is not a new concept. The mining industry has constantly been working with ahighly variable raw material supplied by Mother Nature, from whom we cannot demand quality assurances. Through the processes of exploration, resource and reserve definition, long and short term mine planning and day to day grade control an end product has been supplied which consistently meets our customers requirements, in an economic fashion. When any of these processes fail, then penalties are incurred which can range from increased mineral processing costs to loss of markets and in the ultimate case, failure of a mining operation.

Jan 1, 1992

By Yongjin S

Datong coal Mine suffers from delays and sudden caving of its massive competent conglomerate roof. Detailed geological studies of the nature of pebbles and matrix of the conglomerate and its sparse bedding, joint and fracture structure, gave rise to investigation of water injection to destroy its strength and to control caving. Comparative investigations, including porisity, permeability, compressive strengths and water injection of conglomerate and sandstone led to empirical expressions relating various properties and to guidance for effective injection and caving practice. This new safe roof control practice should be even more improved with further research, including Modelling.

Jan 1, 1992

By Johns AS

Comissioning of a new residue disposal tcluding upgraded classification for none backfill preparation, new variable speed pumps and a new residue dam took place in 1¦76. The system is described.

Jan 1, 1978