Search Documents

Bendigo is AustraliaÆs second-most productive goldfield, having produced some 22 million ounces of gold between 1851 and 1954. Bendigo Mining Limited (BML), the sole lease-holder of the Bendigo Goldfield, is developing a mine that is planned to produce ore from beneath the historical workings for at least the next 25 years. The high-grade Bendigo reefs occur in the proximity of the chevron anticlines, which characterise the goldfield. Typically the reefs display relatively small cross-sectional areas and large (subhorizontal) strike dimensions. They occur in clusters due to interrelated structural controls. Most of the gold occurs as visible grains and laminae, and as such grade estimation is not amenable to ænormalÆ sampling and estimation techniques. The initial phases of exploration and development of the mine focused on understanding and resolving these sampling and estimation issues. In 2005, BML reviewed and updated the March 2004 Feasibility Study, refining the life of mine development strategy. The strategy fundamentally aims to exploit the 11 million ounce Inferred Resource and additional exploration potential by developing the current Kangaroo Flat Mine to produce ore at an initial rate of 450 000 t/yr in 2006/07, expanding to 600 000 t/yr by 2009/10; and developing the Eaglehawk Mine to produce 1 Mt/yr by 2011/12. Ore will be processed initially at the Kangaroo Flat site, and from 2011/12 also at the Eaglehawk Mine 1 Mt/yr processing plant. The two mines will connect underground in 2009. Total ore treatment capacity will be 1.6 Mt/yr, producing 600 000 oz/yr from a head grade of 12.7 g/t gold. The project is planned to operate for 25 years, processing 33.6 Mt of ore producing 13.7 Moz of gold. To achieve this production rate, the exploration and ore delineation programs will require up to 16 diamond drill rigs producing over 200 km of core per year. At the same time, approximately 8 km of on-reef development must be monitored and typically 18 stopes managed concurrently. The processing plants will be located in geographically constrained areas, which will limit the ability for selective stockpiling and campaign treatment.

Jan 1, 2006

By S Meffre, S Golding, K Zaw, J McPhie, R James, S Suphananthi

The Chatree deposit is located in the central portion of Loei Fold Belt, which extends from Lao PDR in the north through centralThailand to Cambodia in the south. Epithermal gold-silver mineralisation at Chatree occurs as veins/veinlets and stockworks with minor breccia in volcaniclastic and volcano-sedimentary rocks of andesitic to basaltic andesite composition and Permo-Triassic age. This preliminary oxygen isotope study mainly focuses on vein quartz of Au-Ag bearing mineralization (Stage 2) and a few samples of late Stage 4 quartz ¦ calcite veins. Quartz from Au-Ag bearing mineralisation has oxygen isotope values ranging from 8.1 to 12.3ë with the lowest values generally occurring at the deeper level (140 m below the surface). The late barren quartz ¦ calcite veins (Stage 4) tend to have higher oxygen isotope values ranging from 11.9 to 12.0ë. The oxygen isotope composition of the Chatree ore fluids were calculated at 250¦C, 300¦C and 350¦C based on homogenisation temperatures of fluid inclusions. The calculated oxygen isotopic composition of the Chatree ore fluid ranges between -1 and 6ë that overlaps with both meteoric and magmatic compositions. This shift in oxygen isotope compositions may relate to processes such as water rock-interaction and/or mixing of meteoric and magmatic fluids. It is interesting to note that the lowest quartz oxygen isotope values are spatially more or less confined to the prominent structures in the centre of the major ore zones. These structures may have been acted as conduits for higher temperature magmatic fluids. The quartz oxygen isotope values increase outwards from the centre of the main ore zones to the margin of the pits possibly due to mixing of magmatic fluids with lower temperature meteoric water. Whole rock oxygen and hydrogen isotope studies are in progress to investigate isotopic trends in the wall rock away from the ore zone. The systematic variation of oxygen isotopes in quartz from the mineralised veins and adjacent wall rocks could potentially be used as a vector to ore. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By J Andrina, D Richards

The Grasberg is a large copper and gold open pit mine operated by PT Freeport Indonesia and located in the high equatorial mountains of Papua Province, Indonesia. The climate is alpine/sub-alpine with little seasonal variation in temperature and rainfall. The annual precipitation varies from about 3000 to 5000 mm over short distances around the Grasberg, but in general, an average daily precipitation of 10 mm per day applies and leaching of the overburden is continuous throughout the year. Mining commenced in 1988, and almost all of the overburden mined up to 2003 was potentially acid forming. The current acid drainage from this overburden is being collected and treated. From 2004 to the end of the Grasberg pit operation in 2014, approximately 70 per cent of the overburden will be potentially acid forming and 30 per cent limestone. A program of laboratory leach columns, field test pads and an instrumented full-scale dump was developed with the objective of defining scale up factors to quantify the acid and metal leaching rates and to evaluate the stockpile geochemistry and control options. The results of an ongoing seven year program have demonstrated feasible scale up between laboratory columns, field test pads and the trial dump in relation to material geochemistry and ARD evolution trends at Grasberg. The potentially acid forming waste types are highly reactive and maximum acid generation rate occurs within two to three years and that maximum copper release occurs within one to two years of exposure. The results also show that the net acid generation (NAG) test provides a good estimate for the potential acid load from overburden types. The chemistry, temperature and oxygen data from the trial dump suggest that oxidation and acid generation is occurring throughout the dump but at a decreasing mass rate with increasing distance from the toe of the dump. It is apparent that convection and/or advection are important mechanisms for the transport of oxygen into and within the dump. Key results and findings of the investigations carried out are presented and the implications of the findings for long-term ARD management at the Grasberg mine are outlined.

Jan 1, 2003

By J Austin, R Bitencourt

Differences between the long-term model (LTM) and mine geology system (MGS) grade control block-outs on a blast block scale can impose difficulties to planning crusher feed grade and tonnes on a monthly to weekly blend basis. Detailed geological input to short-term planning has been integral to improve the performance and reduce risk in six-week to three-month production schedules and local variability in tonnage and grades is often not accurately represented in the LTM. The challenge of producing to combined target specifications from different mine sites in an integrated mine to ship business has been reduced with the creation of blast blockout-based short-term model. These short-term blast block models (STBBM or STM) are robust predictive tools created for upcoming benches of current mining areas by firstly collecting data from the pit in the form of bench and face mapping and projecting the structure and stratigraphy down to the next bench. A wire-frame of the projected contacts based on material destination from production blockouts is created and then checked against the LTM. Blast block data from the bench above including assay results and material logging is extracted and validated according to the projected wire-frames (geozones). Individual blast blocks and a full block model are created for each bench production defined by the STP (bench plans). Data output from the STM is in a compatible format for import into scheduling specific software packages. Additional information is incorporated into the STM to allow querying of drill penetration rates, predicted powder factors, material hardness and feed type to further aid in the production planning process and cost forecasting. To date, reconciliation of the STM has been pleasing and certainly an improvement on the LTM, especially in areas where variability is higher due to geological complexity. Short-term predictions derived from in-pit geological observations allow mine planners to more confidently decide on mining block sizes and schedule tonnages and grades, reducing the risk component attached to developing production schedules based directly upon long-term orebody models and mine plans.

Jan 1, 2005

Many problems occur in recruiting staff to remote mining operations, relating to both domestic and works environments. These are stated, together with steps which have been taken to overcome them. Geographical and climatic conditions applying to the Agnew mining operation are described. Company policies have been established to define criteria for selection of staff, and to define methods by which the criteria are applied.

Jan 1, 1980

This paper mainly studies the creation and optimisation of a doublesymbol random engineering network, by means of developing a set of engineering network project dynamic decisions and an optimisation sustaining system, which can realise engineering network dynamic workout and optimisation. It can provide a good decision for engineers and managers to supervise and manage the construction development and to ensure completion of the construction on time.

Jan 1, 2003

According to the analysis of 126 mine gushing records and the relevant water supply and hydrogeologic condition, the gush can be classified into eight types;cave type,collapse -column. type, subterranean stream type, fault zone type, contact zone type, upper plate type, bottom heaving type and surface water invasion type. The formulae for counting the peak discharge of gushing point are further put forward in this paper.

Jan 1, 1988

Concepts of facies are of proven worth in sedimentology, but have hitherto received little attention from volcanologists. The time is now ripe to develop facies schemes for volcanic products. This paper discusses possible facies applicable specifically to lava flows and ignimbrites, the intention being to explore possible approaches to the problem of recogniz- ing volcanic facies rather than attempting to develop a comprehensive facies scheme

Jan 1, 1987

In his introductory remarks Mr. MacKellar referred to three types of development which may be considered to compete with mining for land use. 1. Total Development - in which he cited urban development, and intensive agriculture. 2. Partial development - in which he cited pastoral, and in this category would come National Parks. 3. Non development - in which category would fall the primitive or wilderness areas.

Jan 1, 1971

A new classification of subduction related (epithermal- / mesother-mal) gold mineralisation styles based on the tectonic framework they occur in, has been found helpful in practice. It offers a ratio-nalisation of exploration efforts during all stages of work.Methodology on the ground during first pass- and follow up explo-ration which has been found effective for the various mineralisa-tion styles is being briefly outlined.

Jan 1, 1990

By Hu Y, Li D, Qu G

In this paper the structural mechanism of the gold - lixiviant complex is investigated. The results show that there are two common characteristics in the outer orbitals for all the gold lixiviants: a) a (Y -type of HOEO to form the L-*Au co-ordination bond, and b) a it type f LUEOs, with symmetry the same as that of 5d orbitals of Au, to form L

Jan 1, 1993

The Metallurgical processes used in the gold industry in Queensland since the 1850's are reviewed. The major upswing in, gold processing this decade has brought the technology of heap leaching, carbon in pulp and carbon in leach, flotation for gold and tailings retreatment to Queensland. In many cases operators have developed or improved these processes to treat difficult ores or to cope with local climatic conditions.

Jan 1, 1989

This paper examines the reform of mining legislation over recent years, the establishment of new Crown land management agencies, and the role of the Crown and environmental groups in nature conservation in New Zealand. It describes the relationship of the minerals industry to the Department of Conservation and environmental groups over recent years, and the prospects for mineral development on the Conservation Estate in future.

Jan 1, 1995

By Rubisov DH

This paper is related to the problems of the mathematical modelling of vibrating screening process and to predicting the screening operation results. The authors propose a model of screening based on the interpretation of granular material segregation on a screen surface as an instantaneous process. Results show an agreement with laboratory and pilot plant tests. Derived formulae can be used for screen sizing and screening result estimating.

Jan 1, 1993

By Collier D

The topaz resource at Torrington in northern N.S.W is currently the subject of a joint research and development programme managed by Pacific Copper Ltd, This programme has culminated in a pilot topaz calcination plant, located at Parramatta, which, through its operation, will establish the commercial viability of developing this mineral as an industrial raw material for both the refractory and fluoride chemical industries.

Jan 1, 1989

By Ryan CG, Cousens DR, Suter GF, Griffin WL

A novel method utilizing PIXE with microbeams following fire-assay has been developed to determine PGE and Au at sub-ppm levels suitable for application in exploration. Analyses of the prills from the lead and silver fire-assay yield Pt, Pd and Au concentrations readily. NiS must be used as collector if the complete suite of PGE is required, but this method is not as Convenient.

Jan 1, 1989

By P W. Cleary, M D. Sinnott

Cross-belt cutters are commonly used for sampling coal. They are generally cheaper than falling-stream cutters, particularly when a cutter must be retrofitted. The major mechanisms thought most likely to lead to sample bias are being investigated by discrete element modelling (DEM) in a project funded through the Australian Coal Association Research Program. This paper describes a benchmark run and the current direction of research.

Jan 1, 2008

The process and control technologies incorporated into the coal preparation plant at Newlands were to be used for the first time in Australia. The commissioning organisation and procedures were set up on the basis that commissioning personnel, while being competent, would be unfamiliar with the equipment. In addition the commissioning process would have to be completed quickly. The organisation coped with all of these problems and more.

Jan 1, 1986

The need to schedule ore production to make maximum use of the strength gained by cem- ented fill during curing is discussed, to show how cement content and hence fill cost can be kept down for any particular operation. Results from laboratory testwork on Isa Mine fill conducted by the author while employed by Mount Isa Mines Limited form the basis of the Discussion

Jan 1, 1973

A paper presenting the results of studies carried out on rotary drill bit life at EluraMine N.S.W.Contributing parameters, including dataon drill operation and geology are compared to the performance observed for the drill bits. Correlation and performance characteristics are presented, relating this data to cutting size distribution over drilling depth.Details are presented of experiencegained through the operation of rotary drillsat Elura.

Jan 1, 1985