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By R Uken G P Whitmore

The coastal dune cordon of northern KwaZulu-Natal is amongst the highest in the world reaching heights in excess of 180 m and up to 2 km in width. It comprises a complex system of Quaternary stacked dunes of various geomorphologies, types and ages. The dunes contain economic heavy minerals which are currently exploited ~20 km north of Richards Bay. Although mining of these ore sands has been in operation for the last two decades, little work has been undertken on the clay-fraction (

Jan 1, 2001

By B Dunstan, F Wirfiyata

PT Newmont Nusa Tenggara (PTNNT) operates the Batu Hijau copper and gold mine and process plant on the island of Sumbawa, Nusa Tenggara (Barat)  NTB, Indonesia. The plant consists of a nominal capacity 120 000 t/d conventional semi-autogenous ball milling crushing (SABC) circuit followed by sulfide flotation to produce a bulk copper concentrate for sale. Process control is effected by a plant wide distributed control system that overlays an extensive integrated programable logic controller (PLC) framework. The system is enhanced by a supervisory expert control system.Since plant commissioning in September 1999, over US$4 million has been expended as part of a systematic continuous improvement approach to optimise plant control performance. Works completed to date include: redesign and upgrade of architecture of the control system to ensure long-term system reliability, security and upgradeability and to provide a suitable platform for advanced control; integration of supervisory and advanced control tools, techniques and instrumentation; and implementation of sound network communication and plant data reporting tools. This paper outlines the evolution of process control and associated systems and tools that contribute to successful operation and ongoing performance optimisation at Batu Hijau.

Jan 1, 2009

By L E. Krause

This paper discusses the considerations for optimum maintenance of critical ore handling infrastructure in order to minimise the cost to the business of maintenance periods. As maintenance periods are a direct interruption to production, time is of the essence and careful management of shutdown periods is essential. The ore pass systems currently in use at Xstrata Copper û Mount Isa Copper Operations are up to 30 years old and have had significant wear over the years. The maintenance of these passes and their brows and chutes in a production situation is a challenge as it can potentially expose personnel to high risk situations in addition to the production interruptions. Some alternatives for mitigating the risk of working in ore passes including plugging and ballooning are described. Criteria are included for selecting a method for the safe entry into a given ore pass. Experience in adapting the method of ore pass plugs and some lessons learnt in the process are also discussed.

Jan 1, 2005

By E Broers, J Goh, S Davies

With recovery being important in optimising the business performance of a laterite and sulfide plant and with water being a precious resource in Australia, there has been increased pressure for companies to improve their methods of improving liquor recovery and improving water recovery in both laterite and sulfide plants. This has resulted in new control technologies such as the Manta Cube being applied on countercurrent decantation (CCD) and thickening circuits which is necessary to improve stability and optimise the liquor and water recovery in these processing plants. This paper describes the benefit of applying these new control techniques on CCD and thickening circuits in some of the mineral processing plants in Australia.

Jan 1, 2009

By D Hodder, M Hoskins, A Rofe

Pasminco Century MineÆs slurry pipeline was commissioned in November 1999. It currently transports zinc and lead concentrate slurries in batch form to the Port facility, 304 km away in the Gulf of Carpentaria. The Pipeline and the Port have gone through several stages of continuous improvement to match the successful ramp-up of the concentrator. Improvements in the Pipeline and Port Operations have included: commissioning of the first slurry pipeline that delivers two products in the same pipeline in batch mode; management of batches throughout the pipeline and port system to minimise cross contamination of both concentrates; operation of the slurry pipeline to achieve high availability of the system; operation of the pump station interfaced with preventive maintenance to minimise unplanned shutdowns; continuous monitoring of pressures throughout the single-station, 304 km slurry pipeline; redesign of the Rotary screw feeder; redesign of the Dryer Control System; installation of a larger Induced Draft Fan; optimisation of the dryer internals to achieve a product of narrow size distribution and pellet integrity; redesign of the stockpile ventilation system; and the development of a surface sealant. This paper describes the early commissioning of both the Port and the Pipeline and the continuous learning and Quality Improvement Project initiated at the Port to focus on concentrate quality given the propensity of the fine concentrate to self-heat during storage.

Jan 1, 2003

By D Wallace, H Guo, B Shen

Appropriate management of the ground subsidence induced by coal mining activities is essential. To assess the effectiveness of grout injection for mining subsidence control, time-lapse ground penetrating radar (GPR) imaging data were collected before and after grouting. The pregouting subsurface responses were interpreted to have changed after grout injection. The changes were caused by injecting the grout materials (flyash and water) into the delaminated strata and permeable fracture zones. The largest distance of the observed GPR event changes at the right end of the main profile is 132 m away from the injection borehole. Although the GPR images could not easily tell if the image changes were caused by the injected ashes or the water, it does suggest that the injection materials had been pushed at least 130 m away from the injection borehole. This is consistent with the borehole scan monitoring, which confirmed that the grout has travelled more than 90 m from the injection borehole.

Jan 1, 2006

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

By Lynce AJ

A method has been developed for the prediction 'of 'the- . performance of a multi-stage grinding=cyclone classification circuit of any degree of complexity on any ore for a wide range `of operating conditions, The-.method involves ;the. s` inu ation b'f the circuit on a digital computer by means of. matheinatical' models ":bf the"' individual units:, the. development of which is- also discussed'., At present, in order to establish 'the!'" charac'teristtics of they ¦ore- and the machines. in mathematical terms;. it is necessary to know'the performance of a , simpl,.e. ; system on tri.e ore - for! one known ,,feed rate and.fe.ed s,l-zing, analysis. ' ,Fiiither work on :the- separate identification 'of the terms defining the characteristics of the ore and the machines may permit the method to be, applied directly to the cj.4ta,derived from small scale tests on ores,

Jan 1, 1964

By I F. Wood

Planning for flooding and assessment of flood impacts are important requirements for mining projects, as they are also for other types of development. With more intense development and concern from the community, supported by government regulatory requirements, assessment of flood concerns and impacts has become of increasing importance. To ensure that flooding issues are fully understood and results presented in an appropriate format, advanced hydraulic analysis procedures have been developed and are beginning to be applied. These procedures must be rigorous in an engineering context but the results must also be readily understood by the community and government agencies. Advanced two-dimensional hydraulic modelling is becoming accepted as an important means of assessing flooding issues for mining projects. With presentation of results from hydraulic models with Geographic Information Systems (GIS), flood impacts can be analysed rigorously and presented clearly. This paper discusses the application of advanced hydraulic modelling in the planning and impact assessment of a major mining project located on a floodplain where there is extensive inundation. The analysis provides for both input to the planning of the project and for detailed assessment of potential impacts. This case study illustrates some important aspects of the application of hydraulic modelling using a two-dimensional modelling to a critical flood design.

Jan 1, 2003

By D S. Stewart, K W. Keskimaki

The Henderson Mine has been utilising a continuous panel caving method to extract molybdenum ore since starting operation in 1976. In the past three decades since the mine was designed, many changes have taken place in underground technology as well as the general nature of the mining business. The impacts of larger scale underground equipment and automation are significant at Henderson and continue to reshape the nature of the enterprise. During the first years of operation in the 1970s, Henderson required almost 2000 employees to achieve full production, today only about 400 people are required to fully utilise the plantÆs capacity. The most recent change to the facility is the conversion from a rail haulage system to an underground crushing and conveying system that transports ore 25 km to the Henderson mill site. This change has required the introduction of large, rubber tired haulage trucks underground and the mining methods necessary to develop the large openings demanded by the trucks and underground crusher. The development of the underground crusher is also the first step to mining the final bottom horizon of the orebody. Along with this move comes an opportunity to almost triple the effectiveness of the mining effort, through higher draw columns and wider draw bell spacing. This final advancement to a totally trackless mine has positioned Henderson well for safe and efficient operation as it enters the 21st century.

Jan 1, 2000

By D Craw

Otago Schist and Klondike Schist are two Paleozoic-Mesozoic metamorphic belts on the circum-Pacific margin in which there has been a long history of abundant alluvial gold mining, but only minor hard-rock gold mining.   Modern exploration for hard-rock gold is ongoing in both belts, and the active Macraes mine in Otago (>2 Moz production) highlights the hard-rock potential of the geological setting of these belts. Hard-rock gold mineralisation in both belts formed in the latter stages of schist exhumation, after rocks were subjected to major regional ductile folding and then uplifted through the brittle-ductile transition. The majority of known hard-rock gold-bearing systems in both belts consist of well-defined, but generally discontinuous, vein swarms. Most Otago veins are hosted in steeply dipping post-metamorphic normal faults and fractures. However, the Macraes mine is hosted by a late-metamorphic shear zone, and much ore is sulphide-impregnated auriferous schist. Goldbearing veins in the Klondike schist are hosted primarily in extensional sites associated with post-metamorphic compressional structures. Some disseminated sulphide mineralisation is associated with Klondike veins and this is important as it extends the exploration target for these veins. No foliation-parallel late metamorphic mineralisation has been identified in the Klondike but exposure is relatively poor compared with Otago and both schist belts are highly prospective for deposits of this type.

Jan 1, 2007

By Zamel GI

The utilisation of fossil fuels, including coal (of which Australia is a large producer and exporter) is a significant contributor to the emission of greenhouse gases. Methane gas, formed during the coalification process, is present in coal seams to varying levels depending on the rank and depth of the deposit. This gas usually escapes to the atmosphere during mining operations without prior conversion to C02 or utilisation as fuel. The quantity of methane released can represent from less than one percent to more than five percent of the carbon content of the coal mined. Per unit of carbon, methane has a greenhouse impact many times that of C02. The emission of uncombusted methane to the atmosphere can therefore represent a greenhouse impact of similar porportions to that of the CO2 formed by combusting the mined coal. However, greenhouse emissions from coal can be minimised by collecting the coal seam methane and converting it to water vapour and the less damaging form, CO2. If such conversion is carried out while performing useful work, the methane can further reduce greenhouse emissions by displacing other fossil fuels. Technology has been developed to allow coal seam methane gas to be economically collected in a pure form, uncontaminated with air. This pure methane can be used to supplement natural gas supplies, to generate power or for the production of chemicals or substitute transport fuels. By collecting and utilising coal seam methane, the greenhouse impact from the mining and use of coal can be minimised, with significant reductions possible in the case of gassy deposits.

Jan 1, 1989

IN presenting the following short paper the writer hopes to illustrate some uses of explosives in industrial work under conditions different to those prevailing on mining fields. This paper is based on experience gained at the Newcastle steel works of the Broken Hill Proprietary Company Limited. The management had decided that as soon as No. 2 blast furnace which is of an improved design was ready to be put into commission, No. 1 blast furpace was to be dismantled and reconstructed to a similar design to No. 2 furnace. This reconstruction entailed the removal of the brick lining of the furnace shaft, and, also the removal and disposal of the,"salamander" and hearth-lining. For the information of members who may possibly be unacquainted with the term "salamander," it might be explained that this term is used by iron metallurgists to denote the mass of iron and slag formed at the- bottom of the furnace, whilst in commission.The method of disposal depends upon the size and nature of the salamander, and in the case under review it was decided to bury it below the hearth of the 'furnace' to be reconstructed. A passage-way was made in the concrete walls of the cast house, and the sand-filling of the cast house removed sufficiently to allow of the concrete foundations of the furnace being reached. This passage-way was extended until the hearth was encountered. The next operation was the removal of the hearth-lining below the salamander. The removal of the concrete was not difficult...

Jan 1, 1921

By B Andrew, L Krois

Ground control systems, including ground control management, play an integral role in the effective and efficient extraction of copper ore at the Xstrata Copper û Mount Isa Copper Operations (MICO). Rock mechanics engineers and support technicians at Xstrata Copper have undertaken a wide range of investigations and actions over the past few years. Outcomes from this work have resulted in the evolution of ground control management practices on the site. Specific areas of improvement include the installation of efficient one pass ground control systems, greater application of sprayed concrete for areas requiring rehabilitation and the addition of new improved products, the removal of obsolete and less efficient products used in standard ground control practice. In some areas underground, the most effective methods to manage ground control hazards continue to be a variation on proven methods that have been in use for many years in the MICO. Ground control systems for developing through the basement contact zone are very similar to that developed in the late 1980s. Similarly, ground control systems have gone through repetitive evolution, whereby some systems fall in and out of favour subject to perceived costs. For example the pouring of concrete shuttering around drawpoints in poor ground conditions has recently been re-accepted as an effective means to manage this poor environment û despite having been previously cast aside as too expensive. Ground control management systems continue to evolve towards the goal of creating a workplace that is free of rockfall-related injuries and provide for higher levels of efficient and effective techniques by which ore is extracted from the ground.

Jan 1, 2005

By F R. M Pires, Y Hasui, A Schrank

The iron ores of Alegria mine are composed of itabirites enclosing minor bodies of high-grade ores. The itabirites are classified according to mineralogical composition in five types: martite-rich, goethite-rich, specularite-rich, magnetite-rich and anphibolite-rich ores. The hematites are martite-rich, magnetite-rich, specularite-rich and more rarely, amphibolite-rich. Other classification criteria of the ores are based on the physical properties and the degree of compaction. As such, the itabirites and hematites can be classified as hard, friable and soft types. The mineralogical/textural evolution of the ores is linked to the pressure and temperature conditions that accompanied the tectonic processes in anphibolite facies and the different degrees of subsequent surficial weathering processes. Petrographic and microstructural studies indicate that the magnetite and amphibole bearing itabirites represent the parent rocks that created the other itabirites and that the specularite itabirites and the hard martite types are related to silica dissolution and redeposition in zones of high and low strain. Most of itabirites ores correspond to chert oxide facies banded iron formation, except the goethite and amphibole bearing itabirite that resemble a silicate or oxide-silicate facies with minor carbonate impurities. The great mass and pods of soft martite itabirites are probably shaley oxide facies BIFs with little volcanic contribution. Trace element contents of the AlegriaÆs itabirites show strong dissimilarities with BIFs associated with volcanism (Algoma type), but closely ressemble to the Lake Superior type, with high content in Cr, Co and low V, Ni, Cu and Zn. Although the absolute contents of REE present in the AlegriaÆs itabirites are, in general very low, the pattern when normalised by NASC is similar to the great majority of the Archean and Paleoproterozoic BIFs elsewhere in the world, and characterised by positive Eu anomaly.

Jan 1, 2002

By P Hodkiewicz, K Noormohamed

Gold deposits in the Chirano district in south-west Ghana are hosted in a variety of structural settings along the Chirano shear zone (CSZ), in Paleoproterozoic rocks of the Sefwi-Bibiani belt. Most gold mineralisation occurs in strongly sheared and hydrothermally altered Birimian mafic igneous rocks and tonalite intrusions within the CSZ. A recent program of open pit structural mapping, core logging, and three-dimensional modelling helped to define deposit-scale structural controls on gold mineralisation. These include strain domains, shear zone flexures, shear zone intersections and vein arrays associated with host-rock competency contrasts. Interestingly, the plunge of higher-grade shoots in some deposits appears to be associated with the intersection of the CSZ and broadly folded Tarkwaian sedimentary rocks, which are not significant gold hosts in the Chirano district. This paper presents the results of 3D modelling that were used to define structural controls on mineralisation in several open pits and one underground mine along a 9 km length of the CSZ. LeapfrogÖ software was particularly useful because it highlighted the orientations of structural features that focused hydrothermal fluid flow during alteration and mineralisation. The improved understanding of structural controls provided two main benefits: near-mine exploration drill targets and better definition of structural domains for resource estimation.

Jan 1, 2009

The concentrating plant of the Broken Hill South Limited was described in Proceedings No. 44, Australasian Institute Mining and Metallurgy, December, 1921, by Wainwright and Read. It was erected on the present site in 1907 and 1908.From that date, the plant has undergone various alterations consistent with metallurgical improvements. By 1925, the timber work of the gravity secti"on had seriously deteriorated, so much so, that, when the machinery was working, the floors and supports vibrated badly, causing heavy maintenance costs.In 1928, it was decided to erect a new gravity-treatment section, to be followed later by a new flotation section.

Jan 1, 1932

By Townsend MG, Evans RB

In Northland, New Zealand, localised large deposits of halloysite clay have been produced by in-situ alteration of rhyolite volcanics of Pliocene or Pleistocene age, which were erupted through pre- Pliocene sedimentary strata and locally through Pleistocene basalt; and which were subsequently onlapped by further basalt flows. Alteration to clay has been a result of both hydrothermal and of meteoric processes, and decreases in intensity of alteration with increasing depth.The raw material is crushed and fractionated to produce a product of less than 2 micron particle size, which is of exceptional whiteness and brightness. The unique properties of the clays render them highly desirable for specialised ceramic purposes.

Jan 1, 1990

Iron formation-hosted iron ore deposits account for the majority of current world iron ore production and consist of three classes: unenriched primary iron formation with typically 25 to 45 wt per cent Fe; martite-goethite ore formed by supergene processes, with abundant hydrous iron oxides containing 60 to 63 wt per cent Fe; and high-grade hematite ores thought to be of hypogene or metamorphic origin overprinted by subsequent supergene enrichment with 60 to 68 wt per cent Fe.Individual iron ore deposits range from a few millions of tonnes to over two billion tonnes at >64 wt per cent Fe, although most are within the range of 200 to 500 Mt. In the Hamersley Province of Western Australia, martite-goethite ores are largely developed in the Marra Mamba Iron Formation, although high (>0.08 per cent P) phosphorous mineralisation is also well developed in the stratigraphically higher Brockman Iron Formation. Whilst the vast majority of high-grade microplaty hematite ore is best developed in the Brockman Iron Formation, this paper provides the first textural evidence of locally significant microplaty hematite mineralisation in the Nammuldi Member of the Marra Mamba Iron Formation, in the Chichester Ranges at the Christmas Creek, Cloud Break and Mount Nicholas prospects. Petrographic studies have identified a high-grade Fe texture composed of nanometre scale plates of hematite in mineralised sections of primary microplaty hematite deposits in the Pilbara and elsewhere, well below the normal depth of weathering or dehydration. The population of nanometre to micrometre scale hematite plates is interpreted to represent various stages of nucleation, crystallisation and progressive growth of hematite from the primary ore-forming fluid in areas that were once iron-rich carbonates or silicates in the BIF.

Jan 1, 2005

By Roberts JD

The design and installation of a major on-line stores and purchasing system, with built-in maintenance reporting and plant register capabilities, needs more than just close attention to computer design details. When the system must be available almost 24 hours a day to a number of mine stores sites, and is used by a variety of mining staff including engineers and stores clerks, as well as by remote purchasing and office staff, then simplicity of use, availability, fast response times, and other human factors become vital. Critical aspects include easy to use screen design, involving a change from the traditional hierarchical menu system, and fallback and recovery to the last transaction. Business, people and systems objectives need to be established at the preliminary design stage, so that results can be measured and corrective action taken. The amount and type of user involvement and training, at all stages from initial design to systems tuning, has a major effect on people wanting to use the system. Active user participation in systems design, data definition and collection, and use of relevant training material is needed. Project management and design problems can arise in working with database oriented computer staff, and certain design features are found useful in ensuring a responsive, robust overall system.

Jan 1, 1983