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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

Quite apart from economic considerations, the following performance parameters must be considered when selecting an explosive for a particular blasting operation. 1. total energy yield/kg, and more particularly, strain energy/kg and bubble energy/kg of charge 2. charge weight/m of blasthole 3. sensitivity of the charge 4. water resistance of the charge The effective division of an explosive's total energy into strain energy (SE) and bubble energy (BE) is explained as is the influence of each energy component on blast results. Because some rocks require a high strain energy for effective breakage, while others are most satisfactorily fragmented by bubble energy, values of SE and BE are more meaningful than those of total energy. Unfortunately, our extensive knowledge of the effects of certain variables on total energy has not yet been completely supplanted by the influence of these variables on SE and BE values. Relative SE/kg and BE/kg values are presented for a range of explosives. The 'charge density of ammonium nitrate/ fuel oil (ANFO)-type explosives is essentially constant throughout the length of the charge; because of their compressibility, slurry

Jan 1, 1974

By Fraser C. J

The township of Yalloum was established in 1921 to provide accommodation for the work force on the sites of the power station and open cut which were to become the basis of Victoria's electricity industry.A company town, Yallourn flourished, and in its heyday in the 1950s the township had a population in excess of 5500 residents.However the town was sited over a valuable coal field. In the 1960s, studies conducted by the State Electricity Commission indicated that excavation of this coal as a continuing development of Yalloum Open Cut was the optimum choice to meet the growing energy needs of Victoria. Operation in what became known as the Township Field commenced in 1979 and the completion of the overburden stripping was successfully achieved on target in 1991.

Jan 1, 1992

By Lumley G, Rowlands D

The overburden slusher (OS) is proposed as a stripping tool that is expected to find application in overburden stripping operations including open cut coal and oil shale mines. OS is expected to combat the effects of increasing depth on the productivity of conventional dragline stripping.Although previously developed stripping techniques have included the use of drag scrapers the OS is sufficiently different as to constitute a new stripping method.A study undertaken at the University of Queensland during 1985 is believed to be the first major study on the use of the OS and preliminary economic results are very encouraging. It appears that the OS has the capacity to remove overburden at a cheaper unit cost than the equivalent powered dragline stripping machine at any comparable depth of overburden. The OS is not adversely affected by increasing stripping depth to the same extent as a dragline. In addition, the action of the OS machine allows for the lowering of spoil face angles, thereby reducing spoil slope stability problems encountered in deep open cut strip mines.

Jan 1, 1986

By Koppe J. C, Costa J. F C L

This paper compares different results for overburden volume estimation assisted by geoestatistics, particularly using kriging methods. The main goal is to obtain the most reliable digital terrain model for the calculation of the overburden volume. The data was collected on an irregularly spaced grid and interpolated values were calculated to provide a denser, more regular data set before volume estimation. The field work was developed at the Butia-Leste Coal Mine, southern most Brazil, where an accurate survey was done using a total station theodolite with electronic data collector. The study was developed in five main steps: data acquisition, exploratory data analysis, spatial continuity measurements, point and block kriging estimation and verification of the results. Data acquisition was carried out on a 5 x 5 in grid. This dense grid provides an exhaustive data set of the real terrain against which data subsets can be compared for the various interpolation procedures and volume calculation. This provides an interesting insight into the influence of the number of data on the estimation error. Univariate statistics were used to compare each data subset and the exhaustive dataset. Ordinary kriging on the data subsets followed by contouring was carried out using Geoeas and Surfer software respectively. A subroutine written in C provided the link between the files generated in Geoeas and subsequent contouring routines embedded into the Surfer package. Omnidirectional and directional variograms were modelled defining the parameters for kriging estimation using Geoeas. Different variogram models were checked through cross validation prior to kriging. A comparison between the magnitude of the differences in volumes calculated with the different DTMs was attained. These final result indicates the sensitivity of the volume obtained to the number of data points. As the number of data points increases the estimation error decreases, but at some point there is no significant decrease in the final volume with the collection of additional data.

Jan 1, 1995

The object of this paper is to show in some detail the mining challenges that have been presented and overcome during the successful development of the main exhaust ventilation drive that will service the Ballarat East mine during its 20+ year lifespan. Topics to be discussed in this paper include the ground support regimes employed, the ground conditions encountered during construction, how the heading was recovered after falls of ground and the effectiveness of geotechnical probe drilling at Ballarat.

Jan 1, 2006

By L Bertoss, D Carvalho

In the last decade, the use of advanced implicit modelling software/algorithms in mineral resource workflows has become a best practice in the mining industry. In most cases, these workflows can easily replicate the level of detail of explicitly modelled geometries, even for very complex deposits. These techniques are flexible and can produce fast results since software is responsible for generating 3D surfaces and solids based on geological and interpretation data. Nevertheless, depending on how unique and complex some deposits are, intense manual editing and input are required to honour the geological context and produce the desired outcome. The current geological modelling workflow at George Fisher Mine (GFM) is based on the semi-automatic built-in tool that generates stratigraphic sequences (stacked lithology layers) based on logging and mapping data. This tool (stratigraphic sequence from Leapfrog Geo™) works for the majority of areas in the mine but fails to capture observed mineralisation pinch-outs in operational areas and at extrapolated boundaries of the deposit. These pinch-outs have the potential to negatively impact grade forecasts if not resolved manually. Using built-in software tools only, the alternative for a more accurate model is to generate each individual layer and adding tens of thousands of manual interpretation points to honour pinch-outs (based on the amount of existing drilling in the mine and number of layers). This approach would require an estimated minimum of two to four years of a full-time employee (FTE) to be exhaustively completed. This study presents an automated approach to generate pinch-out points using a set of Python scripts that only take a few minutes to run. The newly generated points are then combined into the commercial software workflow as interpretation points, honouring observed pinch-outs. The remarkable time difference between approaches removes chance of manual errors and allows mine geologists to spend valuable time in validation and testing of scenarios, ensuring they are more representative of the deposit’s geology.

May 24, 2023

By M J. Ireland, D P. Horne, S J. Simpson

The Sinclair Nickel Project, wholly owned by Xstrata Nickel Australasia (XNA), includes an underground mine, a concentrator, a village, an all-weather airstrip and associated mine infrastructure. The operation is located 70 km north of Leonora in the prospective and historically productive eastern Goldfields region of Western Australia. Xstrata Nickel has successfully developed the Sinclair deposit into a 350 kt/a operation since its discovery in November 2005, with contained nickel metal production to date in excess of 10 600 t, of which 5500 t is from the underground operation.The narrow, continuous, medium-grade Sinclair nickel sulfide deposit accessed by the Phoenix Decline has a shallow 15¦ - 20¦ plunge that is approximately 1000 m long down dip and open at depth to the north. The flat plunge and low-grade nature of the orebody presents challenges regarding the amount of horizontal waste development that can be economically excavated, which in turn affects ventilation, egress, mine services and diamond drilling.The mineralisation is hosted between an ultra mafic hanging wall and a basalt footwall and is being mined using a bottom up, sublevel open stoping method. The stopes are retreated to a central access, filling voids in the process with waste mullock where possible and using cemented mullock fill where end exposure is required. Tight filling the flat dipping hanging wall has proved to be challenging given the angle of repose for the waste mullock fill is steeper than the angle of the hanging wall.Reconciliations of mine performance against the original feasibility study show positive changes and operational optimisations enabling Sinclair to achieve its mining targets in a safe, sustainable and economic manner. This paper discusses the mining operations associated with the first two years of the Sinclair Underground Nickel Project, providing an overview of the various issues encountered and the lessons learnt in the process.CITATION:Ireland, M J, Horne, D P and Simpson, S J, 2012. Overcoming mine design and production challenges at the Sinclair underground nickel project, in Proceedings Narrow Vein Mining 2012 , pp 37-48 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 26, 2012

By Hunter W. H, Wilson I. P, Craig R. W

In September 1988 the Imperial Smelting zinc - lead blast furnace at Avonmouth England, was uprated from its then 52 week annual rated capacity of 90 000 tonnes/year of furnace zinc to 110 000 tonnes. In order to provide sufficient extra feed the sinter plant was likewise uprated in April 1989 by increasing the blowing rate of the sinter/acid plants from 100 000 to 120 000 Nm3/h, effectively a 20 per cent increase. In the 12 months after the uprate zinc production was only 85 000 tonnes. Two years after the uprate zinc production had increased to 100 000 tonnes, but it was not until January 1992 that a rolling 12-month zinc production of 110 000 tonnes was consistently achieved. This paper describes the problems encountered with the uprate and how they have been or are being overcome. It deals chronologically with events starting with the restart of the ISF at the end of 1988 and covers the following issues and their resolution: 1. Initial shortages of sinter due to an offset in uprate timing. 2. Greater difficulties in operating the larger furnace particularly on start-up, the greater tendency for iron production and serious slagging problems. 3. Coincidental timing of deleterious trends in slag chemistry. 4. Refractory problems in the furnace shaft and condenser. 5. Shortages of sinter due to commissioning problems with the wet gas and sinter tip end fans, and difficulties in obtaining sufficient sinter hardness. 6. Unrealised full benefits of the sinter-acid uprate due to a late change in design to dispense with sinter gas recirculation, but offset by successful use of oxygen. In a planned maintenance stop in September 1992 further improvements to the furnace design were carried out to resolve the refractory problems, and with improvements to the sinter plant the furnace zinc output capacity is planned to rise to a rate of 120 000 tonnes/year within two years.

Jan 1, 1993

By D R. Anstey

The growing demand for iron ore from Western Australia has led to an increased focus on the development of magnetite and lower grade iron ore deposits. The need to process and beneficiate the ore from these projects can result in the generation of significant quantities of iron ore tailings over the life of a project. Over the coming decades, the management of iron ore tailings will become a significant aspect of the mining landscape in Western Australia.The tailings generated from iron ore projects differ signifi cantly from other mineral tailings currently produced in Western Australia. Iron ore tailings are generated on a scale not matched by any other mineral process and can often contain asbestiform or potentially acid forming components. New iron ore projects are coming under increased environmental scrutiny because of their large scale operations and the sensitive environments in which they occur. This combination of factors creates some unique challenges for the management of tailings generated by iron ore mining in Western Australia.This paper presents the fi ndings of two studies conducted in recent years to overcome the challenges posed by iron ore tailings. The paper discusses the role of laboratory testing in the development of management strategies for asbestiform minerals in tailings. It also presents a numerical modelling approach for evaluating the rates of rise in the storage of magnetite tailings. The paper concludes by outlining how the findings of these studies can be applied to reduce tailings management costs, lower risks and improve environmental outcomes for the management of tailings from iron ore mining.

Jul 11, 2011

In Australian collieries, solutions to the outburst problem must be implemented in a highly competitive environment which has a low tolerance on negative productivity effects. Solutions are only applicable if the overall viability of the operation remains sound. Minimum time must be spent on alleviation and control measures. This is favoured by simple geology, advanced warning and efficient alleviation and control procedures. Research requirements in support of this include 1. an improved means of predicting the nature and location of outburst zones ahead of the face and, 2. an improved means of measuring the effectiveness of gas drainage. For additional safety at the face, a means of continuously monitoring outburst proneness is required. In general, greater emphasis is required on improved instrumentation.

Jan 1, 1987

The Australian Mineral Industry's growth in the last two decades is directly related to the skill and experience of its consultants in mining, metallurgy, geology, finance, management, marketing, and engineering. The role of mining consultants needs to be re-examined, so that the quality of the service they deliver will continue to be adequate for the 1990's. One means of this evaluation is by examining Case Studies in the strategies and difficulties of developing contract and entrepreneurial research.

Jan 1, 1986

By R Pinksen

The Iron Ore Company (IOC) of Canada Mining and Operations Departments expressed an interest in reducing the amount of oversize material (>1 m × 1 m × 1 m) being produced and its subsequent downstream effects including in-pit sorting and reduction, damage to mobile equipment, and significant delays in the loading pockets and the primary crushers. To achieve this goal an oversize reduction project was undertaken by the mine and to date has significantly improved upon baseline measures.One key approach used to reduce the amount of oversize was the implementation of thicker emulsion. The introduction of a thicker emulsion into the blastholes provided more resistance to the forces created by dynamic water and reduced the infi ltration of the emulsion into the cracks and fissures of the rock mass. Blast results showed reduced amounts of oversize and more consistent fragmentation throughout the muck piles. Additionally, a significant reduction in nitrates leached into the mine water discharge has been realised.To determine the effectiveness of the oversize reduction project, IOC used shovel based camera technology to assess fragmentation presented to the shovel at the digging face. A digital vision system (DVS) was installed on one of the shovels to capture images that were stamped with global positioning system (GPS) locations. A large population of digital images was analysed to produce a robust fragmentation distribution baseline that was used as one of the mine key performance indicators (KPI). Changes to blasting practice were subsequently measured against the baseline KPI to assess effectiveness.

Jul 11, 2011

By Quemard D, Troncoso J

The Gordonstone Project with a capital cost in excess of $500 million will become the largest underground coal mine in Australia. The project development decision was taken on 31 July, 1990 and at 31 May, 1991 construction was approximately 35 per cent complete. The first train of processed product coal will be railed to Gladstone during December 1992. The general theme of this paper therefore will address the planning and development processes at Gordonstone particularly the interrelatedness of technical, production, construction and environmental disciplines to ensure success during operations.

Jan 1, 1991

SASOL Synthetic Fuels has recently completed the design of sampling systems for raw and blended coal feeding the gasifiers at Secunda, South Africa. The new systems will replace manual, stopped belt sampling and have been designed to achieve specific accuracy targets on a daily basis. The sampling system is unusual in the coal industry in that the fines content (-5.5 mm nominal) of the coal is very critical and is to be determined with high accuracy.The sampling system was designed to meet carefully considered target accuracies using methods of modern sampling theory. The heterogeneity of the coal streams involved with respect to the critical analytes was determined by appropriate sampling and sample analysis. The statistical characterisation of the time variation of analytes in the process streams was based on variograms derived from on-line ash gauges. From this point, the design was completed using fundamental statistical sampling theory and some simulation studies. The paper discusses the development of the sampling system design in detail as well as the plans to use the data stream to provide timely alarms when the coal quality deviates from the target specification.

Jan 1, 2002

By T Sylow, A Correa De Araujo, M Gotelip Barbosa

ArcelorMittal is among the largest world’s producers of iron ore. With a geographically diversified portfolio of iron ore and coal assets, it is strategically positioned to serve the network of steel plants, as well as supply the external global market. ArcelorMittal Mining has a global portfolio of 14 iron ore operating units across Brazil, Bosnia, Canada, Kazakhstan, Liberia, Mexico, Ukraine and the United States. Iron ore products include concentrate for sintering and pelletising, pellets, directly shipped fines and lump ore. This paper presents an overview of ArcelorMittal iron ore mines including iron ore typologies and the annual production of each unit. It will also briefly discuss the processing required in order to obtain marketable products.CITATION:Gotelip Barbosa, M, Correa De Araujo, A and Sylow, T, 2017. Overview of ArcelorMittal mining operations and research and development, in Proceedings Iron Ore 2017, pp 161–116 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By J S. Moema, R Paton, J Zimba

Today, most organisations are familiar with the pressure to increase their effectiveness and efficiency, regardless of the nature of their business. Cost cutting and increased productivity are the main themes of many initiatives to ensure the profitability of operations and, ultimately, shareholder satisfaction. It is well known that the cost of comminution to liberate minerals such as gold from their respective ores is a major expense for mines. Comminution costs consist predominantly of grinding balls and electricity. However, there are no national or international standard specifications for grinding balls û on which a single mine may spend several million dollars per month. In addition, in the past mines generally did not specify the minimum requirements when purchasing grinding balls from suppliers. The result is that every supplier has its own grinding ball recipe (regarding chemistry and heat treatment), and is under no pressure to implement a quality assurance plan to ensure that a consistent product is delivered. The resulting variation in the quality of grinding balls leads to increased steel consumption rates and hence increased milling costs. A more stringent quality plan will generally not be welcomed by suppliers since this may entail further investments and/or reduce the production rate. In a sense, suppliers benefit from poor quality grinding balls as this leads to increased sales. Perhaps the main problem is a lack of understanding of the factors that influence grinding ball performance. This paper will describe the factors that influence the wear rate of grinding balls from both a microstructural perspective and a mill perspective. In addition, some insights are provided on the different grinding balls available and ways that users can verify their quality.

Jan 1, 2007

By Camier R. J, Perry G. J

Extensive deposits of brown coal exist in the Gippsland Basin, primarily in the Latrobe Valley. The total quantities of economically winnable coal in this region of Victoria and in other smaller fields are large enough to adequately assure Victoria's future electricity needs and to also provide large quantities for alternative applications, including liquefaction. As a result of the recent conflict in the Middle East attention has again been focussed on the production of synthetic fuels from coal. There have been many investigations over the years into the production of oil from Victorian brown coal. The purpose of this paper is to summarise the scope, objectives and major findings of these studies, with the emphasis on the direct hydrogenation route for converting brown coal to oil. The principal alternative processes are carboniastion and hydrotreatment of the product tar, or gasification and Fischer Tropsch synthesis of liquids from the product gas. The attractions of Victorian brown coal which have encouraged these studies include: ò the vast reserves of Victorian brown coal and the favourable conditions for low cost mining, ò the high quality of the coal (low ash, sulphur and nitrogen contents), ò the high reactivity of the coal giving high yields of product in hydrogenation to liquid fuels, ò the extensive data base available on the resource and its characteristics, and ò the availability of a skilled workforce and extensive infrastructure in the Latrobe Region to support a major resource development project. These advantages have been partially offset by: ò the high moisture content of the brown coal and the cost of drying, and ò the priority previously given to electricity generation in the allocation of the brown coal resource.

Jan 1, 1992

The various risk components to be addressed by explorers and project developers (and their investors) to minimise and/or manage the risk of Pacrim mineral investment are summarised to provide an overview of the issues involved and to set the scene. It then highlights the role of individual Mineral Industry Professionals (especially independent consultants) who are at the heart of any risk reduction or risk management strategy. The involvement of accredited qualified/experienced (competent) and reputable professionals is essential to produce realistic and reliable results that gain and maintain investor confidence. Today, high ethical standards as well as technical competence are sought by government legislation/licensing regimes and initiatives of professional bodies like AusIMM, MICA, Professions Australia, Council of Professions, etc. All attempt to regulate and guarantee reputable individual professional behaviour (particularly in the context of currently perceived high corruption levels in many Pacrim countries). Brief comment will discuss the usefulness of accreditation and ethics codes plus other specific codes (eg JORC/VALMIN and their international analogues in Canada, South Africa, etc) in reducing risks.

Jan 1, 2004

Over the past 12 years screening of materials has undergone a dramatic change in both the types and materials used in screen mats and the quality requirements of the finished product. With the main thrust now on quality and a cleaner product a different approach was needed in the operation of sizing screens. New screen mats with many different aperture configurations have been developed using rubber and plastics.to replace the traditional screen mat of woven wire or punched plate.

Jan 1, 1984