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By Warren R

Croesus Shaft is one of two operating shafts on North Kalgurli Mines Limited's Fimiston lease.At the cessation of gold mining in 1974, the workings at Croesus were allowed to flood. Large quantities of deslimed mill tailings used in filled stopes were washed into the shaft and surrounding drives, making re-access very difficult. The shaft has been desludged from the 9 level to the 15 level, and a loading pocket installed below the 14 level. A vacuum lift unit was installed underground to facilitate the removal of the slime and spillage.Stoping at Croesus was hampered by poor drainage, pumping, and shaft availability. These difficulties have been overcome by utilising an open stoping system for the relatively steep, narrow, high grade stopes. Open stoping has proved to be effective and economic.

Jan 1, 1985

The methods used by the Anglo American Corporation for analysis of long-term metal markets and prices are described. The principal factors affecting the relationships between production costs and metal prices are analysed. These are firstly the type of market, - speculative or consumer commodity, free market or subject to price control; and secondly the rate of growth of demand for the metal. It is shown that virtually all metals will have relatively low rates of demand growth for the foreseeable future, due to market saturation, increased economisation, substitution and product obsolescence. Metal prices have a clear dependance on production costs, however forecasting future costs is by no means simple; amongst other things, account must be taken of changing exchange rates, inflation rates, and the potential for operating more efficiently. The paper concludes by giving brief assessments of the long-term future for aluminium, copper, zinc, nickel and tin.

Jan 1, 1986

A survey of derelict and active alluvial tin and sapphire mines in the Emmaville area of northern N.S.W. as the first step in a pro- gramme of similar surveys to be undertaken throughout the State by the State Pollution Control Commission is presented. Thirty nine individual mine sites in the study area were included in the survey and an assessment made of the current level of impact on the environment at each site by assigning values of "magnitude" and "importance" to a number of impacting factors. Results are pre- sented in matrix form and mine sites ranked in order of impact "importance". Examples of alluvial tin, underground tin/arsenic and alluvial sapphire operations are discussed in detail and rehabilitation programmes proposed for implementation.

Jan 1, 1976

By S McKnight, S Hall

Much of the research regarding the use of bacteria for the oxidation of sulfide minerals has been conducted using pure bacterial strains or synthetic minerals, often under ideal conditions, which does not reflect the conditions commonly encountered in commercially operating plants. This has also led to much conjecture as to the exact mechanism by which bacteria are able to enhance sulfide oxidation and as to which species of bacterial microflora are the most dominant. Recent advances in 16S rNA sequencing has confirmed that many of the bacterial species once thought to dominate commercial oxidation circuits were simply more willing to grow under the culturing conditions used and may only play a minor role in the oxidation process (Rawlings, 2002). Consequently this research will look at bacterial oxidation under conditions more reflective of commercial operations, focusing on the presence of organic carbonaceous material within a refractory sulfide orebody to be sourced from the Fosterville deposit of Perseverance Corporation Limited.

Jan 1, 2004

By Eri G

Ok ledi Mining Limited underwent a major transition from radio based truck dispatching to computerized dispatching for its equip- ment fleet in October, 1996. Modular Mining's Computerized Dispatch System was selected based on reputation and superior customer support. Modular's dispatch system is a fleet management system that uses computer, data communication and global positioning sys- tem technology to produce automatic, optimized haul truck as- signments. Optimization is achieved by equally distributing trucks to shovels so that truck queuing and shovel idling times are mini- mized. Computer illiterate mine operations personnel had to overcome a rather steep learning curve to use the high technology equipment. fortunately the system was able to be configured to use bitmap

Jan 1, 1997

George Fisher Mine, near Mount Isa in northwest Queensland, has been producing Pb-Zn-Ag ore since the late 1980s. It consists of two separate underground deposits, George Fisher South and George Fisher North. These two deposits are drilled and modelled separately but are crushed and hoisted as a single stream. The Pb-Zn concentrator in Mount Isa processes ore from George Fisher Mine and Black Star Open Cut, with production also from the Isa Lead Mine until January 2006. This paper outlines the steps involved in setting up a robust reconciliation system for George Fisher Mine, in conjunction with requirements of the Pb-Zn concentrator, Black Star Open Cut Mine and the Mount Isa Lead Mine. Good quality input data and commitment to training have contributed to establishing a robust and effective reconciliation system. Reconciliation data has highlighted several other continuous improvement opportunities.

Jan 1, 2006

The Mt Todd Project is located 42 km northwest of Katherine in the Northern Territory. The identified mineral resource estimate for the Batman gold deposit is 66.7 million tonnes (Mt) grading 1.4 grams/tonne (g/t). Proved and Probable Ore Reserves total 42.3 Mt grading 1.5 g/t. Orebody definition and reserve estimation is based on extensive percussion and diamond drilling. Exhaustive bias analysis comparing grades produced from different drilling techniques has been undertaken. Similarly, detailed check assaying programs have been run to validate grade data produced by commercial laboratories used during the exploratory drilling phase. Significant biases were established from both studies and appropriate 'corrections' were made to drillhole databases prior to final resource and reserve estimation. 3D geostatistical modelling has been utilised for resource and reserve estimation, with specialist consultants contracted for this work. At all times, interpreted geological controls on mineralisation, provided by

Jan 1, 1994

By White B

The domestic and commercial use of underground space dates back to Neanderthal man living in caves. There are many examples worldwide of the imaginative use of underground excavations, either left by mining or purpose-built. World living trends indicate that an increasing percentage of the population is living in and around major cities. Environmental, social and economic pressures associated with urban expansion can be partially catered for by a well-planned and integrated underground space regime. This paper addresses the types of underground development that are complementary to the economic and environmental pressures associated with urban expansion and high density cities. The paper explores the implications of mining and exploration technology and civil engineering, as well as the ancillary professional disciplines (legal, architecture and planning, sociology and education).

Jan 1, 1997

By Lennox A

In an attempt to increase underground productivity Coal and Allied has introduced a continuous haulage unit into it's Moonee colliery. A second unit is planned for Nallarah colliery in the near future. Both systems will be roof mounted or monorail type and manufactured by Joy Manufacturing Pty Ltd. The introduction of these machines is seen as a logical step in improving the efficiency of mining with continuous miners. This could be in conjunction with longwall mining in the rapid development of gate roads or, as in the case with these machines, as conventional development and extraction units. The advantages of the continuous haulage system are; Relatively low cost. 2 Ability to obtain high productivity in irregular or disturbed coal reserves not suitable for longwall mining. 3 Increased worker safety with the elimination of shuttle cars and the majority of trailing cables. 4 Increased productivity independent of soft or difficult floor conditions. At the time of writing the Moonee installation is 6 months old. The Nallarah machine is due for delivery March 1988.

Jan 1, 1988

By Jackson S

An investigation into different aspects of importance in the understanding of explosibility of hybrid mixtures of coal dust, air and gases potentially found within mine workings through a comprehensive laboratory program of explosibility tests was conducted. Plotting of test results revealed that conditions of potential explosibility could be described using two dimensional flammability limit surfaces- for coal dust/oxygen; methane/oxygen; and coal dust/methane mixtures. From these plots, the three dimensional flammability envelopes defining the explosibility of the coal dust/methane/oxygen mixtures can be defined and illustrated for a coal sample. The surfaces of the three dimensional envelope describe limits which separate inert mixtures of coal dust and methane at varying oxygen levels from those concentrations which are ignitable under defined conditions. It is considered appropriate to generalise that the geometric shapes of these limit regions are applicable to all type classifications of coal dust. There are practical applications of these results to the underground environment.The action of free radical initiators in the propagation of a methane gas explosion was examined for its applicability to the flammability of coal dust/gas/air mixtures. The oxides of nitrogen or NO x radicals have influence upon the lean limits of flammability of hybrid mixtures and this is illustrated by use of three dimensional coordinate geometry. Gases can be introduced to the underground environment through the exhaust gases of diesel equipment. It is concluded that radical species can substantially increase the flammability of gas and dust flames and as a consequence raise risk of mine atmosphere explosibility.

Jan 1, 1998

Basic premises for evaluating special characteristics of gold-bearing porphyry metal systems stem from their contrasts with properties of the class as a whole. Included features are differences in geologic, thus tectonic, environments, subtle but real differences in the proportions of accessory metals Mo-Ag-Au that are regionally and within some regions, tempo-rally distinct, contrasts in the Ag:Au ratios, petrological-geo-chemical as well as isotopic differences between intrusive suites, the age and nature of host terranes, contrasts in alter-ation style, and zoning variations of mineralogical and physical properties of rocks. These properties are linked in various ways in different regions and suggest that in large gold-bearing systems where gold may be uniformly distributed, environ-ments of emplacement, and compositions or sources of igneous "progenitors" may dominate in importance over processes, and that systems in which gold is zoned are processes-dominant.

Jan 1, 1990

By A Ruotsalainen

Mining industry sees a comprehensive future in optimisation and process control. High resource utilisation is a starting platform when lower operational costs with higher rate of return are the target. Simulation is quickly penetrating the mining industry as a planning tool. A discrete event simulation helps to visualise the reality of a mine and the various mining processes, which typically include a fair degree of complexity. What-if scenarios can help to determine the impact of occurring changes to production. Understanding of critical points in the layout and resource allocation at an early stage can help to optimise the material flow. The obtained information may then be used as proposal or confirmation of the system applicability and economy. Simulation is a way to fine-tune and optimise the resources within. It helps to predict system sensitivity to various aspects. Although simulation today is used typically in a feasibility stage, there is an opportunity to continue using simulation for further process enhancement. In the future simulation will without doubt be used increasingly as a dynamic simulation and continuous improvement tool. This paper discusses the use of OptimineÖ simulation tool in resource optimisation. Some examples describe the way the tool operates and how it helps to view the technology, mine layout and operational data.

Jan 1, 2003

By Heidecker A

Several types of drainage structure providecost-effective environmental controls for water supply to Charters Towers and its mining industry. Drainage groves maintain bank-levee, channel, pool, and spring structures. Failure of drainage structures leads to anoxic fermentation of channel fill releasing residues, such as arsenic, which would otherwise pass harmlesly by fixed on sedimentary particles.Experiments along drainage structures indicate that productive agroforestry could be integrated with expeditious development of groves to cope with environmental change.

Jan 1, 1990

By A H. Hofstra, G P. Landis, P Emsbo, A G. Hunt

Models of the evolution of the hydrothermal systems that form porphyry Cu (Mo-Au) deposits are compromised because aqueous magma-derived fluids in the ore zones of most deposits have changed from their original magmatic compositions as a result of cooling, depressurising, mineral precipitation, brine-vapour unmixing and fluid-rock reactions. However, in deep quartz-rich, sulfide-poor veins from numerous porphyry type deposits, we have identified parental fluids trapped in inclusions at near magmatic temperatures and pressures above the brine-vapour unmixing solvus. We have analysed these inclusions for bulk salinity, density, solute chemistry, helium isotopic ratios and elemental composition. These parental inclusions contain 35 - 70 volume per cent bubble, are low to moderate salinity, contain up to ten mol per cent CO2, and commonly contain a chalcopyrite daughter crystal. Our results indicate that these Cu-rich fluids transport Cu from a plutonic complex below upward into a hydrothermal system, where decompression, cooling, unmixing and water-rock reaction drive ore-mineral precipitation. Na/Cl ratios greater than one indicate that in addition to chlorine, sulfur and/or carbonate must play a key role in Cu transportation. Helium isotope ratios indicate that between ~15 and 100 per cent of helium in these fluids is mantle-derived. We suggest that in addition to He, volatiles from mafic magmas in the mantle are also likely to supply CO2, Cu and S to the fluids that form porphyry copper deposits. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

The last decade has seen a dramatic change in the. size and complexity of mining and mineral processing projects in Austral- asia. Major projects of today are vastly different from major projects of the 19.50's. This change has in turn resulted in a change in the role-of consultants whose contributions have been increasingly in the provision of specialist services and less in the form of overall project design and construction supervision. It is anticipated that, the specialist function will continue to represent the principle mode for consultant participation in major, projects. However, by means' of international affiliation, the development of comprehensive engineering and project management capabilities and possibly as a result of Government intervention, it is expected ,that local consultants will assume an increasing degree of participation in.the overall project design and supervision Function.

Jan 1, 1975

Pyrite is one of the principal Au-bearing minerals in refractory gold ores. Significantly high Au concentrations of up to 5200 ppm are present in pyrite. Pyrite hosting high levels of Au is also enriched in As. Pyrite as an unwanted mineral ends up in wastes and constitutes one of the primary sources of As in the mining and metallurgical wastes. Arsenic can be readily released to the environment due to rapid oxidative dissolution of the host pyrite under atmospheric conditions. In order to determine the form and occurrence of arsenic in pyrite, micro-X-ray absorption fine-structure spectroscopy (XAFS) spectra were collected from a range of arsenical pyrite grains having different morphologies and a range of arsenic and gold concentrations. All the pyrite grains are characterised by the dominant edge aligned with As-1 valence state. In pyrite, arsenic atoms substitute for S atoms that are in six-fold coordination about each Fe atom. XAFS data suggest that As atoms occur in clusters within the pyrite structure. In addition to As-1, fine-grained, inclusion-rich and framboidal-type pyrite grains have a second As species at ~11 875 eV corresponding to As5+. This As5+ species in pyrite is highly variable and attributed to the oxidation of arsenic exposed on the surfaces of pyrite.

Jan 1, 2008

The current drill-and-blast method of tunnelling is cyclic and, for this reason above all others, has a future application potential which is lower than that of continuous methods. There is scope for progress in several facets of today's drill-and-blast tunnelling. But even if each of its unit operations and the synthesis of these were to be optimised, this conventional method will, in the long term, fail to be a serious competitor for tunnelboring machines (TBMs), roadheaders and the like. If its role in tunnelling is not to decline at an increasing rate, drill-and-blast will need to be transformed into a continuous system. Boring and cutting machines consume considerable energy (and expenditure) in creating rock fragments which are smaller than those required by muck-handling equipment. In this respect, blasting is more efficient. Mechanical methods are also less versatile and flexible and, when planning proceeds on a basis of meagre or inadequate geological data, cannot be costed as accurately. Currently, research gains for TBMs and roadheaders are greater than those for conventional tunnelling. If (as is likely) the disadvantages of mechanical methods continue to be reduced at a greater rate, the swing away from drilling and blasting will gain momentum.

Jan 1, 1987

By Hainsworth D, Winstanley G, Gurgenci H, Corke P

Past experience has shown that the automation of the dragline swing motion requires real time monitoring of the bucket position. A current project at the Centre for Mining Technology and Equipment (CMTE) is aiming to achieve this using machine vision. The hardware platform is a Datacube MaxVideo 200 system. The images are obtained by a fixed camera installed on the dragline boom. The field of view is large enough to include the bucket in all possible configurations. Standard chain coding and run-length coding algorithms are used to process the video image. The three-dimensional bucket position is calculated by combining the output of the machine vision system with the rope length data obtained from transducers installed on drag and hoist drums. This information is then fed into a control computer which takes corrective action to suppress bucket oscillations before they reach dangerous levels.

Jan 1, 1995

Managers are demanding efficient use of their resources and part of this demand is leading to the idea of integrated audits for Occupational Health and Safety (OH&S), quality and the environment. It is possible to construct audits which test the compliance in this area with standards established by management systems and it may be that such an integrated audit of a site could reduce the time of auditing and be equally effective as three separate audits. However, this is only a maybe. To do an audit on all three aspects when they are not fully integrated results in more time wastage than doing three separate audits. But organisations are not structured around the audit process (some financial managers may query this statement). The organisational management systems are put in place to achieve the organisational goals - presumably in an efficient and cost-effective manner.

Jan 1, 1995

By Valery W, Morrell S, Loughlin P, O&apos

Traditionally, blasts in mining operations are designed to prepare the in situ rock mass for excavation and transport without much consideration being given to the downstream comminution processes. Blasting is in fact the first step in a chain

Jan 1, 1998