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By A Karrech, E Hamdi

The uncertainty of geomaterials properties is commonly encountered in resource engineering applications, especially in mining engineering where the rock mass texture, joints, fractures and damage zones can impose the mining method and operation cycles. In the present research work, we focus on the elastic properties of rock masses. We use stochastic numerical simulation of fractured rock masses to estimate their Young moduli. The procedure starts with field mapping campaigns which are conducted to evaluate the locations, dip angles, strike and trace lengths of pre-existing fractures. We develop statistical law parameters of the natural fracture network to represent the weakness patterns. In addition, we use HLA-Dissim, a recently developed and validated Matlab program, to simulate the propagation of monochromatic longitudinal waves and derive the equivalent elastic modulus of fractured rock masses. Such procedure applies within a simulation domain, which is greater than an Elementary Representative Volume.At a second stage, we conduct finite element simulations to validate the previous approach. The matrix and the actual fractures zones are reproduced in the model to mimic the natural set-up. The block is excited on particular positions and its response is evaluated on predefined spots. Real field rock fracture mapping data and monitored single-hole blast induced vibrations are used to validate the theoretical and numerical approaches discussed herein. Comparison between the simulated and measured vibration records shows a great agreement which confirms that the proposed methodology has a full potential to predict and optimise multihole/multidelay blast-induced vibrations.CITATION:Hamdi, E and Karrech, A, 2015. A methodology for rock mass characterisation to control blast-induced vibrations, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 89–96 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

Getting it right is a very profitable outcome. Shareholders would ideally like to see their directors get it right all the time on the major economic decisions. But it is very difficult for mining directors to get it right all the time in such an uncertain environment. Primary decision-makers of companies with significant stakes in the mining industry should get it right much more frequently. The legal measures of evidence (beyond reasonable doubt and on the balance of probabilities) can be used to determine whether grade estimates (a key revenue variable) are realistic. The application of this approach can be far reaching. More frequently correct decision-making would result in more effective allocation of limited resources (capital and labour). In turn, this would result in higher financial returns and a more extensive mining industry.

Jan 1, 1994

By Martinick WG

In July 1986, Cable Sands (W.A.) Pty Ltd commenced mining for mineral sands at Minninup, approximately 16 km south of Bunbury, Western Australia.The area being mined is from the heel of the foredune to the rear of the hind-dune. The vegetation is mostly native vegetation with some old degraded pasture.The mining operation will be by suction cutter dredge, with continuous dredging, mineral separation and re-depositing of the sand.

Jan 1, 1986

By E Thomas, L McCallum, G Dale, J Bennett, K Reardon-Smith, S Raine

Sustainable closure of coal mines in Australia to a safe, stable, non-polluting condition remains one of the industry’s biggest environmental and social challenges. A significant proportion of mines in the Bowen Basin of Queensland have dispersive spoil. Based on an estimated area of 20,000ha and a rehabilitation cost of AUD$100,000 to AUD$150,000/ha, the instantaneous rehabilitation liability for the Bowen Basin alone is estimated at AUD$2 to $3 billion.Dispersive spoils present problems in post-mining rehabilitated landforms due to increased potential for surface and tunnel erosion, compromising the ability to achieve fundamental mine closure objectives of a safe, stable, non-polluting and self-sustaining post-mining landform (Minserve, 2004). Dispersion results in clay particles being mobilised and transported in water, even at low flow velocities (So et al., 1998; Minserve, 2004), and blocking of soil pores, resulting in surface sealing, crusting and reduced permeability (DNR, 1997; Vacher et al., 2004) which, in turn, further increases runoff (Dang et al., 2018).CITATION:Dale, G, Reardon-Smith, K, Thomas, E, Bennett, J, McCallum, L and Raine, S, 2018. A process-based approach to mine rehabilitation decision making using Bayesian modelling and risk-based principles for dispersive spoil rehabilitation, in Proceedings Life-of-Mine 2018, pp 106–109 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 25, 2018

By Leahy G. J, Moxon N. T, Nicol S. K

Experimental work is described in which extremely dilute aurocyanide liquors are treated with novel surface-active complexing agents to produce a hydrophobic aurocyanide species. Subsequent aeration of these liquors causes accumulation of such species at the air-water interface and the aurocyanide complex is transferred to a froth concentrate. A detailed performance assessment of this process is made and this knowledge used in the design of a pilot plant facility. Early results indicate the feasibility of the selective recovery of aurocyanide ions from reclaimed residue dam water (approximately 0.2ppm Au) with upgrade ratios of the order 180:1. A further study was made applying ion flotation to the recovery of gold from a carbon-in-pulp (CIL) feed liquor (approximately 1.0ppm Au). The probable economics of this process compared to conventional CIL processing is also described. Successful development of countercurrent ion flotation for concentrating solids-free gold solutions may offer a lower cost alternative to existing gold ore processing technologies, or in more secondary applications such as concentrating dilute gold solutions or heap leach runoff. The technology may also have more generalised applications to other heavy metal process- Ing.

Jan 1, 1991

Mine geologists have access to an economic mineral deposit, production parameters and secure exploitation title. They are well placed to understand ore formation and should contribute to the effective exploration of company mine property. Application of their special skills has been curbed by pre-occupation with production duties and by company re-engineering, including staff reductions. Contributions to exploration have been diminished and personal development inhibited. Modified management is required. Participation in mineral system studies and in exploration research comprise part of the basis for the re-emergence of mine geologists on the exploration scene. Changes in investment strategies in the minerals industry may create new employment opportunities. With regard to estimation of resources and reserves, the competence of practitioners who are incapable of disclosing their methods in transparent terms is under question. Ethical standards are also under public scrutiny because of some notable malpractice. Independent auditing may hecome more intrusive. While understandable in a market context, it reflects poorly on the profession. More substantial effort in public communications can improve the credihility ofthe industry and equip practising mine ceolouists for snider responsihility.

Jan 1, 1997

By Grady B. V O, Cavell K. J, Ault A. R, Newman O. M G, Malcolm J. McPhersqn

Cyclic voltammetry (CV) has been evaluated as a technique for monitoring the quality of an industrial zinc sulphate electrolyte. The basis of the method involves measuring a change in the polarisation of the zinc nucleation reaction at an aluminium surface and relating this to the impurity content and/or the overall quality of the electrolyte. Specifically, the technique aims to be able to indicate and quantify detrimental synergism between impurity elements, something which traditional analytical techniques are incapable of providing. The technique has found some success with regard to monitoring glue additions in a range of metal electrolytes. It has been found that investigations by a number of workers over the past 15 years have produced variable and often misleading results due to the inadvertent use of commercial purity aluminium working electrodes. It has been shown that impurity elements in the working electrode can give rise to a range of responses that are not obtained when pure aluminium is used and that the response is variable due to the lack of surface homogeneity of commercial purity aluminium electrodes. Furthermore, it was demonstrated that previous detection limits reported in the literature were based on the presence of additional peaks in the cathodic scan and not polarisation effects. The results of this study have shown that when a pure aluminium working electrode was used, the method was incapable of detecting any change in polarisation for an electrolyte containing three common impurities (Co, Ni and Ge), at concentrations that would significantly reduce optimum electrolytic performance. A range of methods was tried to sensitise the technique, including raising the temperature and acidity, and adding antimony in order to induce some synergism. In all cases the polarisation response was unchanged. Consequently, apart from the commercialised application for monitoring additions of antimony and levelling agents such as glue, CV has very limited application as an electrolyte screening technique.

Jan 1, 1993

In contrast with mining in areas close to the main centres, mining in remote areas is characterised by comparatively high initial investment and relatively high running cost for the life of the mine. This is because of:the real cost of establishing and running the operation at a location distant from the necessary infrastructure; and the perceived risks priced into their costs by the multitude of suppliers involved in the project. Optimal co-operation between the mine and the supplier in developing the right rela tionship and the correct technical solution permit both cost elements to be reduced. This re duction may well mean the difference between success and failure. This paper examines the possibilities for optimising the contribution of the equipment supplier to the overall success of the process. Issues covered include the necessity to provide more than merely equipment fit for the purpose , but also the need to maximise the benefits of equipment ownership over the life of the mine. A simple method of determining the optimum timing for equipment replacement or rebuilding is proposed . Furthermore the maintenance contract (or performance agreement) is suggested as a means of leveraging the supplierÆs commitment to the mining operation. The specific examples are based on experience with mobile equipment but the methodology has relevance to other equipment and supplies.

Jan 1, 1998

The development of present methods of pillar extraction has evolved from the very earliest of hand mining operations which were limited in scope by venti- lation and transport considerations. Conservation and safety considerations also have led to the current shortwall operations with conventional equipment and powered supports. The shortwall methods have had significant effects on safety, costs, con- servation, flexibility, and other aspects of pillar extraction. The present stage falls short of the ideal but is some guide to prediction in what direction may lie the ideal methods for the future.

Jan 1, 1974

By E Jak, M Shevchenko, D Shishin

One of the key aspects to develop sustainable metallurgical production is to ensure that the predictive power of thermodynamic tools is brought up to a new level of accuracy and reliability. Exploring new polymetallic processes, integrating primary and recycled materials, means utilising the uncharted areas within the Cu-Pb-Zn-Fe-Ca-Al-Mg-Si-O (major) – Cr-Na (slagging) – As-Sn-Sb- Bi-Ag-Au-Ni-Co (minor) slag-solids-metal-matte-speiss-sulfate system. This requires extensive integrated experimental and thermodynamic modelling study, which is underway at PyroSearch at the University of Queensland (UQ).

Aug 21, 2024

By Brown N. R

This paper attempts to highlight some of the problems encountered in the economic exploitation of the deeper coal seams by opencast mining methods. The major cost elements of three methods of overburden removal are examined in relation to the overall cost of winning coal from deeper-lying coal seams. The three overburden removal methods examined are dragline stripping and two systems combining dragline stripping with shovels and trucks at varying depths of overburden. A dragline is, undoubtedly, the most cost effective system of overburden removal for depths of up to 30 metres but it is suggested that, when dealing with incremental overburden depths in excess of 30 metres, engineers should consider carefully the possibility of using a shovel and truck operation, or other system, to augment the use of a dragline.

Jan 1, 1986

By Misra V. N, Spottiswood D. J

In recent years the column flotation process has gained worldwide acceptance for processing various types of minerals under different circuit configurations. In an age when real prices of many mineral commodities are in decline and mining and labour costs are rising in real terms, it is more important than ever that concentration processes be not only efficient but also cost-effective. The column flotation process can give better metallurgical performance as well as involve lower capital and operating costs compared to conventional mechanical cells.This paper reviews the literature on columns and the effects of various column parameters on performance of the column flotation process. The history and principles of operation of the column flotation process are briefly discussed by way of introduction.

Jan 1, 1995

Gold mineralisation was first noted in 1983 at the Wapolu Point area of Fergusson Island, Papua New Guinea (PNG) during a follow-up regional reconnaissance program. Subsequent exploration programs through to late 1987 completed 22,147m of costean trench sampling, 553 aircore/RC/diamond core drill holes (16,970.5m total) and metallurgical testwork, predominantly on the Wapolu grid in two mineralised areas.Subsequently in 1988, geostat-istical global and polygonal resources were calculated for the main mineral-ised zones, Didigayagaya and Dagwalala. In 1992, a 'probable total reserve' of 1.9Mf @ 2.4g/t with a 1.2g/t cut-off was calculated for these prospects.

Jan 1, 1994

By Jansen N

Production from the narrow, high grade silver-lead-zinc orebodies below 15 level commenced in mid 1985.Geological, mining research and recent mining experience determined that a mechanised drill, fire and muck cycle would be the most suitable method.Ground conditions are predicted to be worse than in other cut and fill (MICAF) areas at Isa Mine, owing to the increased depth, more variable dip of the orebodies and the increased effect of major geological structures.Mechanised ground support and tight filling techniques feature in controlling these expected adverse ground conditions.

Jan 1, 1985

By Fair A, Oxenford J

Syncrude Canada Ltd operates one of the largest open pit mines in the world at Fort McMurray in northern Alberta, Canada. In 1993, Syncrude mined and processed 131.2 Mt of oil sands to produce 67.0 MBbls of synthetic crude oil (SCO). This represents approximately 13 per cent of Canada's crude oil requirements. In addition to the oil sand mined, Syncrude moved approximately 96 Mt of overburden ahead of the mining operation in 1993. Since start-up in 1978, Syncrude has had outstanding success in improving the safety and reliability of its operation. Much of this success has been achieved by reducing risk through the application of new and improved technology. This improved safety and reliability has resulted in, among other things, very significant improvements in operating costs and profitability. This paper discusses some of the technology applications that have been introduced at Syncrude to reduce risks to people, equipment, operations and the environment. Three specific examples will be discussed in detail to demonstrate how reductions in risk have greatly improved the operation.

Jan 1, 1994

By J Zhang, O Ostrovski, C Zhang D Cai, Q Wang

The conventional CaO-SiO2-based mould fluxes are not suitable for high-Al steel casting because of the strong reaction between silica in the flux and aluminium in the steel strand. In the process of casting of high-Al steel, flux composition changes; with the decrease of the silica concentration and increase of alumina. Knowledge and understanding of the effect of the Al2O3/SiO2 ratio on flux structure and properties are useful for flux design for the high Al-steel continuous casting. This paper investigated the effect of the Al2O3/SiO2 ratio on structure, viscosity, phase composition of fluxes quenched at different temperatures and heat transfer of CaO-Al2O3-SiO2-B2O3-Na2O-Li2OMgO- F fluxes. It was found that flux melting temperature increased with the increase in Al2O3/SiO2 ratio. Viscosity of the flux melts increased significantly with the increase of the Al2O3/SiO2 ratio from 0.7 to 1.2, reaching the maximum value, and then decreased with further increase of the Al2O3/SiO2 ratio. Raman spectroscopy analysis revealed that the change of the Al2O3/SiO2 ratio led to the change of aluminate and silicate structural units. The turning point for viscosity was attributed to the change in the degree of flux polymerisation. X-ray diffraction (XRD) analysis showed that increasing Al2O3/SiO2 ratio increased crystallisation tendency of the fluxes. Heat transfer measurement by infrared emitter technique (IET) revealed that increasing Al2O3/SiO2 ratio led to the decrease in heat flux which is correlated well with the increased crystallinity of the flux. The results suggested that the flux with Al2O3/SiO2 ratio 4.3 is the best candidate among the studied CaO-Al2O3-based mould fluxes for casting of high-Al steel.

Aug 21, 2024

By D Morrison

Backfill is usually considered a necessary evil that contributes little to the principal objective of the operation, ore production. Consequently, it is relegated to an auxiliary role in the operation with minimal equipment and resource allocation in planning and is only superficially considered during feasibility studies. In many mines, the inadequacy of the design and operation of the backfill system ultimately leads to frequent delays, excessive costs and, in the worst cases, major instabilities which result in reduced ore production and lost or unrecoverable ore reserves. The primary objective of backfill is to prevent the progressive deterioration of mined out excavations. With the exception of narrow vein operations, it is too weak to alter the mining induced stress regime and control stress concentrations caused by stope extractions. However, the direct benefits of backfill include the possibility to consider a wider range of mining methods, recovery of 100 per cent of the planned resource and the selection of a stoping sequence that minimises the regional stability problems that cause production shortfalls in the later years of mine production. Indirectly, backfill is a practical means of solving other issues, such as waste disposal, that impact the viability of mining. In Australia, the geotechnical conditions of many mines are becoming more difficult and increased attention to the importance of backfill is warranted. This paper describes realistic aspects of backfilling and the positive impacts a well co-ordinated fill system can have on mining activities as a whole. Examples are presented where an integrated approach to backfill systems have offered significant benefits to the operation.

Jan 1, 1998

The necessity for good management and economic working in our mines and ore-dressing sheds is impressed upon us by the present low prices of all our metals. Silver, lead, copper, and tin have all suffered a heavy decline during the last six or twelve months, and many mines have been shut down simply on account of the low market value of the ore produced. After fully considering the position of the mining industry. I am convinced that considerable improvements will have to be made to make it as prosperous as it ought to be. The most obvious of these improvements are good management, good machinery, and as little interference by directors as possible. If these conditions are insisted upon and carried out efficielltly a poor mine may have a chance to weather the storm.There is no doubt that the present depression is the refilult of over-speculation and general loss of confidence by which the whole commercial system has been affected, and every branch has suffered more or less, mining not excepted. It has suffered heavy losses in the past, and the future is not over bright we are, therefore, compelled to be careful in everything by which mining is affected and savings can be secured.

By E Widzyk-Capehart

The conventional ammonium nitrate fuel oil (ANFO) loader utilises a pneumatic system to control the flow of ANFO (via rotary actuator/ball valve) and air (via an auxiliary air valve). This system, though relatively simple and reliable, has several drawbacks with respect to ease of control and level of automation. In this paper, a radio frequency (RF) remote control for explosives charging is discussed. The system design incorporates electric solenoid valves to control the rotary actuator and the auxiliary air valve. All operations associated with explosives charging are selectable at the remote and are completed according to a modifiable time sequence. This allows the following charging sequence to be reduced to a single momentary application of the remote:removal of water from the hole prior to charging with ANFO; charging of the hole for a preset but adjustable period of time; and removal of the remaining ANFO from the ANFO hose. A specially developed remote switch allows the operator to maintain two-handed control of the ANFO hose whilst achieving full control of the charge-up process. Failsafe electronic architecture is incorporated into the systemÆs design to increase safety to the highest level. Should the RF remote control fail, a wired remote is included in the system to allow for the charging process to continue, albeit at a reduced level of control. The application of the RF remote control system in an underground explosives charging operation minimises and/or eliminates many problems associated with the use of the conventional charging system. These include: the wet-hole problem, trip and entanglement hazards, air embolism and the two-man loader control requirement. The developed remote control unit proved to be effective at removing water from wet holes leading to increased face advance per drilling operation. It proved to be economically feasible, allowed for an increase in systemÆs dependability and safety factor and for a truly one-man operation which resulted in reduced manpower.

Jan 1, 1999

The economic significance of a fundamental understanding of the mineral pyrrhotite is dis- cussed. Particular emphasis is placed on the relationship of other sulphide minerals to the pyrrhotite when it is the major sulphide mineral present in an ore body. Studies of the Kambalda nickel deposit are used to give a better under- standing of (a) the genesis and other character- istics of a particular ore body (b) the textural relationships between pyrrhotite and other sul- phide minerals (c) magnetic properties of natural pyrrhotite, and (e) the oxidation and supergene processes that take place in a sulphide ore body.

Jan 1, 1972