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By D S. Scovira

The effect of blast vibration on highwall stability is a common concern for many open pit mines. Vibration in such a case is a typical near-field blast vibration situation. Vibration modelling in the near-field of a blast requires consideration of both the amplitude and frequency attenuation of waveforms with distance. Most existing blast vibration models are designed for far-field vibration and do not simulate the frequency attenuation and its effect on waveform shape. With the advent of electronic detonators it is desirable to quantify the effects of blast delay on the amplitude as well as the frequency of blast vibrations. A suitable modelling tool is proposed here. At present, a blast vibration model with double attenuations(amplitude and frequency) has been developed at Orica. The present model simulates the amplitude and frequency attenuations separately using different transfer functions. The amplitude attenuation is modelled according to the non-linear relation between the peak particle velocity (PPV) and the charge weight scaled distance established from the signature hole vibration. The frequency attenuation is modelled with the signal broadening based on KjartanssonÆs transfer function û a linear model for attenuation of waves. The model is capable of taking multiple sets of signature waveforms as input to improve the modelling accuracy of the wave propagation in the geology at a site. The screening effect of the earlier firing holes in the path of a later firing hole is taken into account on not only the amplitude, but also frequency attenuation. The present blast vibration model is suitable for modelling both near-field and far-field blast vibrations. It yields reasonable agreement with measured field data for the near-field vibration examples discussed.

Jan 1, 2007

Territory Iron has seen fit to revive the old Frances Creek iron ore mine some 30 years after it ceased operations in AustraliaÆs Northern Territory. The key to this revival has been the changes that have happened since market forces, infrastructure limitations and a cyclone combined to force its closure. As it breathes life into this old mine, the Company is serious about its responsibilities to its shareholders, to its workers, to local and regional communities and to the environment. This paper addresses how Territory Iron has approached technical, operational and regulatory issues that apply in Australia. Some insight may be gained into the myriad of tasks that mining companies face to revitalise an old mine. These tasks vary from employing the latest exploration tools, best practice drilling, sampling and modelling of orebodies, optimisation of pit designs and schedules, maximising product value by blending, optimising infrastructure usage and minimising capital and operating costs. All of this has to take cognisance of commercial, environmental and other issues including Native Title.

Jan 1, 2007

By M Castle, D Mendelawitz

The Marra Mamba iron ore in FortescueÆs Chichester Range project area occurs as a very flat dipping series of waste shale and iron ore beddings. These beddings vary from millimetre thickness to several metres. The ore material generally exhibits a moderate degree of competence when subjected to ultimate compressive strength (UCS) tests, normally failing at up to 60 Mpa. However, the strength of the beddings is markedly less when subjected to the tensile forces imposed by the cutting action of the surface miner. Two surface miners of differing age and sizes were tested over a period of almost three months. These machines produced a product that had not been subjected to dilution by blasting and of such a size that primary crushing is not required. The machines were able to cut all ferrous material presented to them with varying degrees of success. Material containing higher quantities of manganese were broken but caused catastrophic wearing of the picks. During the trial the volume of material produced by the two machines in various strength materials very closely matched the manufacturerÆs estimates. The major impact on costs per tonne related to the wear on bits, which in turn varied with the bit design and composition. Bit design and composition testing is continuing.

Jan 1, 2007

By M L. van Kampen

The Resource Management Act 1991 provides for activities to be classified as permitted, controlled, restricted discretionary, discretionary, non-complying or prohibited in district and regional plans. This paper looks at the use of the prohibited activity status to restrict, in particular, mining. Often the use of prohibited activity status for mining appears to have no basis other than the negative perceptions that the local community and/or the planner drafting the plan has toward mining and quarrying.   The paper will address the current appeal regarding the use of prohibited activity status now before the Court of Appeal, and the history to the litigation. The relevance of the outcome of the appeal to the minerals sector will also be explained.

Jan 1, 2007

BHP Billiton Mitsubishi Alliance, or BMA, is AustraliaÆs largest coal miner and exporter, and is currently responsible for around a quarter of AustraliaÆs total annual coal exports. BMA and its predecessors have been part of the Queensland mining scene for around 40 years, developing world-class mines, a port, overseas markets, and an international reputation for quality and reliability. From its production base in QueenslandÆs Bowen Basin, BMA produces a broad suite of coals which are supplied to 73 customers in 24 countries. BMA was formed in June 2001 as a partnership between BHP Billiton and Mitsubishi Development Pty Ltd, under which the two companies share equal ownership and management of eight Central Queensland coal mines û Goonyella Riverside, Broadmeadow, Peak Downs, Saraji, Norwich Park, Gregory, Crinum and Blackwater û and the Hay Point coal export terminal near Mackay. This case study focuses on Peak Downs Mine, which was the second largest open cut mining operation to be developed in the northern Bowen Basin for the original CQCA Joint Venture. The first coal was mined in April 1972 and today, Peak Downs has a production capacity of over nine million tonnes of coking coal per annum. The mine is located 30 km south of Moranbah and 195 km south west of the Hay Point port facilities. Coal is mined by open cut mining methods using six draglines and two truck/shovel stripping fleets for overburden removal. Coal seams are mined using excavators and front-end loaders and 210 tonne capacity coal haulers.

Jan 1, 2007

By G F. Brent, R D. Hart, C Carr, F Felipe

In underground operations, where copper, gold and other metals are mined, the open stopes can be backfilled to stabilise surrounding workings. This fill may consist of tailings from the processing plant, usually mixed in slurry with a binder such as ordinary Portland cement (OPC). Extensive use is made of tailings in OPC-based paste fill, cemented hydraulic fill or cemented aggregate fill applications. A large underground operation such as the Mount Isa Copper Operations utilises over three million tonnes of backfill per annum. Geopolymers offer an alternative binder system with significant environmental advantages over OPC. Geopolymers are formed by polymerisation of aluminosilicate precursors in an alkali medium. They generally form products with superior strength characteristics as well as increased resistance to degradation, particularly under acidic conditions. Geopolymers have lower carbon dioxide emissions associated with their manufacture than OPC and offer further potential advantages, such as the use of less water and more waste materials. The application of geopolymers to weak material systems such as mine backfill has not been widely studied. The aims of this investigation were to assess a range of Australian mine process wastes for suitability as feedstocks in fill applications and to construct a range of these cemented minefills using a geopolymer binder. The physicochemical characteristics of each of the wastes are discussed as well as how they ultimately contribute to the geopolymer cement through direct replacement of OPC. Results from various tests on the candidate geopolymer fill formulations are presented and the potential of such fill formulations to replace OPC in mine backfilling operations is highlighted. The significant potential contribution to reducing greenhouse gas emissions from the use of geopolymer-based mine backfill across the industry is noted. Conversion of a single mine, such as the Mount Isa Copper Operations, is shown to match the reductions in greenhouse gas emissions due to the current total installed photovoltaic electricity generation capacity of Australia. A similar examination of wastes available to a gold mine could potentially yield new binders for use in established or new fill systems.

Jan 1, 2007

The importance of the accurate determination and interpretation of the bulk density and porosity of a given iron ore deposit is very often disregarded or neglected. Large amounts of time and money are spent on delineating and testing orebodies, and yet one of the most important factors in resource evaluation is sometimes estimated or, at best, determined from existing data from similar deposits. The Thabazimbi and Sishen South iron ore deposits are two well-known economical occurrences of high-grade iron ore in South Africa. Both these deposits formed as secondary enrichment of banded iron formation lithologies. Ongoing density studies on both these deposits are underway and results thus far proved very effective and necessary. Small-scale methods are used to determine average values for different ore types on both deposits. These values are used in resource estimation and geophysical interpretation.

Jan 1, 2007

Mine site rehabilitation is the repair of the disturbance caused by mining on the immediate mining area and also on the surrounding environment. The long-term objectives of rehabilitation can vary from simply returning an area to a safe and stable condition, to restoring the mined land to a state as close as possible to its pre-mining condition, capable of being self-supporting and having a beneficial final land use. This paper investigates the importance and benefits of environmental planning, in particular for rehabilitation, and how input into daily operations can allow mining to progress with limited impact on the surrounding environment. It will also identify some of the key mistakes currently made during mining which could be averted by implementing prior planning and incorporating environmental consideration into daily operations. A number of rehabilitation opportunities will also be detailed for the different stages of the life cycle of a coal mine.

Jan 1, 2007

By G Billing a, D Gribble, E Hall, D Varga

The theoretical benefits of electronic detonators have been reasonably well documented. To support this, a practical comparison was made between the performance of the standard shock tube system, NONEL, and a high precision electronic system, HotShotÖ, at the Sunrise Dam Gold Mine. The expected benefits from electronic detonators to Sunrise Dam were identified prior to the trial. Based on these, a number of objectives were set to demonstrate the value of the HotShot system. These are an improvement in fragmentation leading to an increase in productivity, less oversize rehandling, increased throughput and more uniformity in muck pile movement. To maintain the integrity of the trial, the nominal timing of the shots was kept exactly the same, thereby restricting any performance improvements to the precision of the electronics. Accordingly, adjacent shots were chosen with consistent geology. Video footage was taken of the blasts and vibration monitoring was carried out by fixed geophones throughout the mine. Spot heights of the muck pile swell were taken immediately after the blast and heave profile graphs were generated for comparison. Video footage was taken for a period of three hours for both shots to analyse cycle times of the excavator and trucks. PITRAM data was also collected for analysis. As far as practicable, the ore was taken to the same finger on the run-of-mine (ROM) pad to assist in single sourcing for the crusher and to allow oversize to be separated out. From specific metrics taken during the trials, it was shown that the expected improvements due to the high precision timing of electronics were realised in all areas.

Jan 1, 2007

By A Robertson

Australia has been slow in adopting the use of underground space as a part of our urban planning process. Australia has one of the highest levels of tunnel advance per capita per annum in the world, yet the use of underground space in our cities appears difficult for our planners and politicians to comprehend, not withstanding the general availability of good quality rock and contractor expertise in Australia. However, the lack of space in our urban areas is being highlighted as our major cities expand outwards and people and businesses gravitate towards city centres. Typical potential underground space uses include car parking, self-storage and archiving facilities, water storage, underground quarrying, small industrial facilities and another layer of traffic (electric and fuel cell) and services network. Historically, blasting in high density population areas has resulted in blast vibrations and blast overpressures exceeding the limits, which in some case have been set extremely low in terms of peak particle velocity (PPV). This makes conventional blasting difficult, often requiring low charge weights per delay and associated small blast sizes and slow advance rates. However, the introduction of new technologies, such as computer aided drilling, electronic delays and low-energy explosives has made this task considerably easier. Although more expensive than conventional blasting, excavation by blasting using these products and technologies in relatively good quality ground is believed, in most cases, to be less than the cost of mechanical excavation. In this paper, the authors look at innovative trends in underground quarrying, underground commercial space and tunnelling and put forward their concept of future excavation demand, future product requirements and technical specifications to the drill and blast community.

Jan 1, 2007

By R Hindstr÷m

The demand for iron ore has increased dramatically in the last years and is forecast to remain on a stable high production level for years to come. ItÆs expected that the world economy is facing a stable continuous growth of iron ore to two billion tonnes and more over the next decades (Beddows, 2007). Furthermore it is expected that the existing and known high-grade ore resources will decline, and the iron ore industry will be forced to implement more and more advanced beneficiation plants. As a consequence of the more complex beneficiation requirements, there will be a need for modern solutions for iron ore dewatering that are reliable mechanically as well as cost effective and with high capacity per unit at the same time. Conventional vacuum filtration methods have been the most prevalent in fine iron ore dewatering. Product quality needs, lower ore grades, complex mineralogy and energy costs have resulted in iron ore producers seeking better solutions for dewatering, in particular pelletising feed. New advanced filtration methods have been introduced to the market. This paper describes how these modern methods are answering the needs of the industry. Performance of advanced dewatering technologies (pressure filtration and ceramic capillary action filtration) for iron ore applications has been studied, and the findings are based on both industrial and pilot scale experiences on different materials. For example, the results show that the cake moisture content of iron ore pelletising feed can be optimised more effectively by using modern filtration technologies. By selecting the most suitable and adjustable equipment, the effects of variations of feed material on downstream processes can be minimised and the possibilities of processing more difficult raw materials to high-quality pellets are better. The Larox Corporation develops, designs and manufactures industrial filters and is a leading technology company in its field. Larox is a full service solution provider in filtration for separating solids from liquids. As such, this paper compares the new developments in this market area with the prevailing known vacuum filtration technology, but focuses on a comparison between capillary action filters and rotary vacuum disc filters (RVDF). The trade name CeramecG is used to differentiate the Larox filter from the generic term.

Jan 1, 2007

By D B. Donato

Gold mining cyanide-bearing solutions can pose a risk, cause significant wildlife deaths and adverse public relations and result in non-compliance with regulatory conditions. The International Cyanide Management Code for the Manufacture, Transport and Use of Cyanide in the Production of Gold (the Code) was developed as a voluntary code to encourage industry-wide improvements in managing cyanide responsibly. The Code requires design and implementation of robust monitoring programs for compliance under the following standards of practice: 4.1, 4.4 and 4.9. A robust monitoring regime can be complicated as each processing and tailing system is different. The following systems are commonly used in Australia: carbon-in-leach (CIL); carbon-in-pulp (CIP); heap leach process ponds; tailing waste disposal systems; peripheral discharge, central discharge and in-pit disposal. Some terrestrial wildlife can be denied access by fencing tailing storage facilities (TSFs) or other physical barriers, therefore limiting wildlife interaction with cyanide-bearing tailing and solutions to mainly birds and bats. While wildlife monitoring programs for processing and TSFs contain similar core attributes, it is necessary to adapt monitoring to take into account the site-specific features of each system. These core attributes are discussed in this paper, with reference made to cyanide concentration and associated methodologies. The issue is considerably complicated if tailing solutions are deemed or discovered to be toxic to wildlife. Essentially cyanides are required to be measured to gain an understanding of the concentrations to which wildlife may be exposed. This usually equates to measuring the cyanide concentration of solutions entering and leaving a tailing system. To assess the risk to wildlife presented by tailing and heap leach systems it is necessary to monitor both the hazard (cyanide concentrations) and the exposure (live wildlife species, presence and interaction). These tasks need not be arduous and a system of simple frequent monitoring has been developed and implemented for Code compliance. The wildlife monitoring developed by Donato Environmental Services (DES) and used at mining operations departs from the industry norm. It documents observer effort, live wildlife presence, habitat and behaviour in a tailing system, as well as deaths and carcasses. A greater understanding of wildlife cyanide toxicosis associated with this monitoring approach will enable mining companies to adopt a proactive approach to significantly reduce, or preferably eliminate, the impact on wildlife and assist in gaining Code compliance.

Jan 1, 2007

There are available today many various types of mixing systems, tank types and process liquors confronting the process designer of gold adsorption circuits. This short paper is to give the process designer an insight into the special mixing requirements for resin-in-leach and resin-in-pulp, plus the advantages and disadvantages of the various mixing systems that are available to agitate the required tank shapes. An understanding of the latest developments in this important process area of gold production is addressed and information given on the results of resin degradation in various tank sizes over long periods of mechanical agitation.

Jan 1, 2007

By G W. Scott, R C. Johnson

Hypogene alteration zones have been described as a precursor to high-grade haematite deposits in Australia, Brazil and elsewhere. This alteration is described as being below or distal and is typically magnetite-carbonate-silicates reflecting Mg - Fe metasomatism. This paper describes, without genetic implication, the mineral zonation and possible structural control on mineralogic variation within the Tilden Mine, a concentrating grade haematite deposit in Michigan, USA. In contrast to the high-grade deposits, these variations are not peripheral to the orebodies but are the ore. The deposit occurs within the Negaunee Iron Formation, along the southern margin of the Paleoproterozoic Marquette Range Supergroup basin. The regional structure is a fault-bounded west plunging syncline within the crustal scale Great Lakes Tectonic Zone, which forms the boundary between Archean granite-greenstone and gneissic terranes. Local structure consists of second-order anticlines and synclines with variable northwest and southwest plunges. The interaction of sedimentation and diagenesis within growth fault controlled basins, along with a possible metamorphic and/or hydrothermal overprint has resulted in a complex series of ore types. For modelling purposes, the deposit is divided into geologic domains based on both lithology and metallurgical response in the laboratory and in the plant. Mineralogic variation is recognised within individual mineral grains; at blast pattern (10 - 15 m) and development drill hole (100 m) scales.

Jan 1, 2007

By D MacKenzie

The Rise & Shine Shear Zone is a shallow-dipping Cretaceous late metamorphic shear zone formed in a compressional environment. The Shotover mineralised system is dominated by normal faults with well-defined vein systems that cut across Miocene schist folds and faults related to the inception of the Alpine Fault. Despite the geological differences between these mineralisation systems, they share many common features of hydrothermal alteration that have resulted in disseminated gold in altered sheared schist. The most distinctive feature of both systems is the abundant ankeritic carbonate that has formed from decomposition of metamorphic chlorite. Excess iron from this alteration reaction combined with hydrothermal sulphur to form sulphides that host the disseminated gold. The chlorite decomposition reaction was reversed in the latter stages of both mineralisation systems, and this was accompanied by further gold emplacement in the Rise & Shine system.   Both alteration systems involved initial decomposition of metamorphic albite, followed by deposition of albite as a vein mineral in the latter stages. The fluid flow that yielded the disseminated gold was controlled by microshears that pervade host schists, in strong contrast to many Otago Schist vein systems where host rock alteration is absent. The ankeritic alteration in the Shotover and Rise & Shine mineralised systems has increased the volume of mineralised rock, and may have made suitable targets for large-tonnage, low grade gold deposits.

Jan 1, 2007

By C Menzies

Hydraulic Monitor mining at Solid EnergyÆs Spring Creek Mine has proven to be a safe and effective method of extracting steeply dipping thick seams at production capabilities approaching one million tonnes per annum.   This paper traces the development of Hydraulic Monitor mining from its initial introduction into old workings at Strongman Mine, its refinement at Strongman 2 in shallow, thick and steep workings, through to its introduction into the deep, very thick seams at Spring Creek Mine. This last step of the progression came with all the added complications that come with depth, particularly flammable gas.   This paper will describe the various changes in mining conditions that dictated the performance of the monitor, how the mine layouts were changed to adapt, and the various operational systems that were put in place, to allow a safe and productive operation.

Jan 1, 2007

By J McNee

Pike River Coal Limited (PRCL) is developing the Pike River Coal Mine in the Paparoa Ranges of New ZealandÆs South Island. The mine is being developed to extract a coking coal deposit of the Brunner Seam, some 46 km northeast of Greymouth, using a combination of continuous miners, road-headers and hydraulic extraction.   The mining area is located within Department of Conservation (DOC) land and is adjacent to the escarpment of the Paparoa Range and the Paparoa National Park. The mine will use its elevation advantage to hydraulically flume coal from the working faces to the pit bottom area where it will be slurried to approximately 35 per cent density of solids and pumped down a slurry line to the coal prep plant some 10.5 km down the Pike River Valley. The coal will be sold on the export market as a high quality coking coal for international steel making.   PRCL faces significant challenges to achieving the goal of cost effective production. The remoteness, high rainfall (greater then 6 metres per year on average), temperature variation and restrictions on access to this subalpine environment have driven the project to develop some distinctive solutions. These include the establishment of survey control in such a difficult environment with vertical and sub-vertical rock faces, significant vegetation and steep slopes by using helicopter survey, aerial photography and LIDAR (Light Detection And Ranging) aerial survey. PRCL has also commenced designing the placement of the main ventilation fans in an underground chamber in the stone drive.

Jan 1, 2007

By C B. Valentin

It is acknowledged that the analysis of iron ores using X-ray fluorescence (XRF) for major and minor elements is best carried out on fusion discs. This method of sample preparation eliminates mineral and particle size effects which can lead to biased results when using pressed powder pellets. However, the fusion disc method is costly as it requires a high capital investment in platinumware, requires experienced operators and uses expensive fluxes. Also, the dilution effect complicates the analysis of trace elements. For many applications, such as exploration and mining control, the method of XRF analysis of iron ores by pressed powder pellet probably provides data of adequate quality. Kumba Iron Ore, an iron ore producer in South Africa, recognises this and carries out most analyses of iron ore by pressed powder pellet and uses the automated fusion method mainly for certification of in-house calibration standards and quality control (QC) samples that are used for validation of pressed powder pellet method purposes. Automated fusion is also used for analysing the composite export shipping samples. All the other exploration, production, despatching and plant operation samples are done by the pressed powder pellet method. Automation of sample preparation procedures should improve the quality of data for pressed powder pellets. To compare the precision of the three methods of sample preparation and XRF analysis, 20 aliquots of a QC standard were prepared and analysed by each procedure/preparation method. The results and statistical data on the most important elements, Fe, K2O and P, are as shown later in Table 2.Clearly the precision is best for the auto prepared fusion discs, as expected, and worst for the manually prepared pressed powder pellets. However, the data generated from the auto prepared pressed powder pellets compare remarkably well against those from the auto prepared fusion discs.

Jan 1, 2007

By G S. C Murray

Major mining projects are developed with the assistance of lending institutions who provide hundreds of millions of dollars in funding over several years, and of course expect those funds to be returned with interest. Two Australian banks have adopted the Equator Principles, an emerging financial industry benchmark for assessing and managing environmental and social risk in project financing. Project financiers have encountered environmental and social issues that are both complex and challenging, particularly with respect to projects in the emerging markets of Asia-Pacific and elsewhere. There are many recent and historical examples of failures by resource companies to effectively manage their environmental, social, safety and security risks, some of which have caused the project to fail completely, and some of which have caused the temporary cessation of production. These events put the financial institutionsÆ funds at risk through inadequate management capacity and non-compliance adversely affecting the ability of the borrowers to repay the loans. They can also reflect adversely on the reputation of the lending institutions. In assessing these risks, lenders are increasingly looking at the track record of the borrower in its country of origin and in other countries where it operates. Lenders are wary of companies that have one standard for operations in a developed country, where the regulatory environment may tightly control what they do, and another standard for operations in countries where the regulatory regime is perhaps less stringent. Lenders may require environmental and social reviews or audits to be conducted on their behalf by competent third parties prior to a loan being approved, and annually over the life of the relationship. The mining industryÆs concept of the unwritten æsocial licence to operateÆ is highly relevant in relation to the delivery of community benefits that are sustainable post-mine closure. This paper provides examples of recent practices that support financial viability and sustainable development, as well as examples of some failures that have put lenders at risk.

Jan 1, 2007

This paper will address this question from the point of view of a drill and blast engineer or researcher working in open cut and underground mining operations. The paper will establish a common set of reference standards for high-speed imaging and data capture, which engineers and researchers can apply when deciding which type of imaging technology is appropriate. It will present an overview of current image analysis technologies and practices in use across a range of appropriate scientific fields and draw lines of commonality of approach between these fields and the field of mining and blasting applications analysis and research. In addition, the paper will examine the different technologies from an image quality and data stream reference point, ease of operation, cost, and reliability parameters. Finally, this paper will present an argument for the hybridisation of established and new technologies which could provide a more beneficial approach to the use of imaging as a tool of quality control, research and analysis in the mining based industries. This will include a novel approach to digital high-speed imaging and data analysis in the field, which should deliver high-quality images and data analysis in a time frame that is more appropriate to the need for immediate action, analysis and problem solving.

Jan 1, 2007