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The paper outlines the history and current status of the VALMIN Code and sets out the background, methodology, results and recommendations of the Independent Review of the VALMIN Code undertaken during 2001 under the Chairmanship of Ian Goddard. The paper is based on the final report of the Taskforce, which was submitted to the Board of The AusIMM for consideration.

Jan 1, 2002

By B Nielsen, H Lehto, J Rohleder, C Robben

Sensor-based ore sorting is being increasingly used to reduce the amount of low-grade and waste material processed in mineral concentrators. This type of preconcentration provides bottom-line benefits to users by reducing the amount of energy, water and consumables, as well as reducing capital cost. Existing operations can increase metal production, while previously uneconomic deposits and low-grade stockpiles can also be exploited. The technology can also be used to separate ore types for selective processing. The path to implementing sensor-based sorting may include:• geometallurgical evaluation• first inspection testing to investigate sensor response• bench-scale testing where sensor selection is not obvious or for difficult applications• performance testing in full scale sensor-based sorting machines• larger scale site-based piloting with a temporary semi-mobile plant installation. Sorting requires material to be suitably prepared and presented to the machines and typically this consists of crushing and screening to limit top size and optimise liberation. However, where material streams are suitably sized and prepared, additional equipment may not be required (e.g. the sorting of semi-autogenous grinding (SAG) Mill pebble streams).This paper presents a case study of economic upgrading of gold ore, by preconcentrating with sensor-based ore sorting. The case study examines sorting amenability, test work, the feasibility study through to implementation, with associated flow sheet development. The development process is analysed and evaluated with a view to rationalising the process for development of future projects. In addition, limited financial modelling based on expected results is shown to illustrate the benefit to the operation.CITATION:Nielsen, B, Rohleder, J, Lehto, H and Robben, C, 2017. Sensor-based ore sorting to maximise profit in a gold operation, in Proceedings MetPlant 2017, pp 131–146 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017

FROM time to time articles have appeared in the technical press on the interesting subject of surface combustion. The theoretical part of the problem has, for practical purposes, received ample consideration in those articles, but the number of practical applications of surface combustion referred to has generally been very small.It is the writer's object to review some recent developments in surface combustion, and also to try to arrive at an estimate of its advantages and possibilities. It is not necessary for this purpose to dilate upon the phenomenon of surface combustion itself. Many interesting things have been said on the subject by Pro£. W. A. Bone, of Leeds, to whose researches the recent developments are largely due. A few illustrations may make clear what is meant by surface combustion.Prof. Bone, in an experiment, took a platinum crucible, which he heated in the flame of a Meker-burner. Then he turned the gas off for a second, and, opening the stop-cock again, allowed the combustible mixture to impinge upon the crucible, thetemperature of which was still well below the ignition temperature of the gas. Although no flame was visible at this stage, it was soon clear that, nevertheless, the gas and air had continued to combine, as the crucible would attain a red heat after a few seconds.Another instance of surface combustion was shown by a Mr. Fletcher, in 1882. He placed an iron ball, weighing 3 lb., on a slab of fireclay, heated it for a few seconds with a blow-pipe, and blew the flame out, leaving the gas-mixture still...

Jan 1, 1915

In understanding the consequence of existing law, and the likely implications of its reform, it is necessary to comprehend the logic of the situation that the law provides individual decision makers and how that situation would be adjusted by reform. In particular, the way in which natural resources, including minerals, are used and managed is influenced by the definition and structure of property rights that the law provides. Property rights are enforceable claims to use or to benefit from resources. An example is a mining licence that allows its holder to extract minerals in a specified area. Property rights establish the structure of incentives, opportunities and constraints within which resource use decisions are made, ie the logic of the situation, and hence influence the use and management of resources. The extent and type of mining in New Zealand, for example, reflects the rights that miners have to extract minerals, and their rights to benefit from mining as against their duties to compensate landowners and pay royalties. This paper describes the characteristics of minerals that are relevant to the definition of property rights, analyses the implications of alternative property right arrangements and describes the existing situation.

Jan 1, 1988

WMC was a late entrant into Indonesia in mid-1996, but had considerable experience and success in exploring in Asia, particularly the Philippines since 1988. Given the geological similarities to the Philippines and IndonesiaÆs superior æcradle to graveÆ Contract of Work (CoW) tenure system, the entry into Indonesia was a logical decision but nonetheless a result of detailed planning. At the time of WMCÆs entry, Busang in Kalimantan was still a 60 moz wonder and the euphoria of this apparent discovery had overflowed into every aspect of exploration. Many junior mining companies and tenement speculators were clamouring for properties in Kalimantan, whilst other serious and capable explorers had to compete for properties and exploration personnel in an era of high and often unrealistic expectations. The picture in late-1998 and through 1999 is dramatically different, as the worldwide downturn in the price of most metals coincides with financial and social crises throughout most Asian countries. The impact of this has been particularly severe in Indonesia and when coupled with the negative sentiment of the Busang fraud has resulted in an exodus of junior companies and also some of the majors. This is understandable given the much publicised social unrest, uncertainty of government, mooted changes to the eighth generation CoW, increasing illegal mining and heightened community expectations. The reality however is somewhat different and although clearly a crisis in many respects, it is also a time of great opportunity.

Jan 1, 1999

Operational effectiveness is fundamental to any operation, becoming highly topical in those experiencing less than optimal output from their fleets. It is all encompassing aiming to identify those factors that could be improved within production and suggesting solutions in order to optimise the existing fleet and obtain the greatest capital return on expenditure.Argyle Diamond Mine (ADM) is a large open cut diamond mine located in the East Kimberley region of Western Australia, approximately 180 km south of Kununurra. It is owned and operated by Rio Tinto on a two week on/two week off roster fly-in/fly-out from Perth or drive in/drive out from Kununurra. Through benchmarking the operation between January and June 2002, a study was undertaken allowing identification of areas falling below target. Following this, analysis of annualised hours and production downtimes were undertaken to quantify the potential gains of improvements in these areas. Strategies were then identified as stated in the 2002 mine plan, in operational effectiveness meetings, and by staff members. This project aimed to maximise direct working hours through determination of the main issues hindering performance. External and internal factors were considered and a continuous improvement program (CIP) was developed. The CIP aimed at internal site-based improvement teams to identify and implement solutions for improvement on a day-to-day basis.

Jan 1, 2003

Validation and Simulation of Optimised Compressive Crushing Ores and aggregates are used in countless applications all around in the society. The frequent and escalating usage of these natural resources requires efforts aimed at not only making do with what is available, but also undertaking actions to improve the production yield and the processes involved. This strive to improve the performance and efficiency of existing crushers and crushing processes has brought about research concerning optimisation of crushing plants as well as theoretical optimisation of crushing. Previous work shows that different applications and different materials require different compressive crushing in order to accomplish a theoretically optimal size distribution. These optimisation results, obtained by genetic evolutionary algorithms and evaluated with so called fitness functions, convey the theoretically optimal number of compressions and their corresponding compression ratios. Presented in this paper are thus some laboratory crushing tests, which are conducted in order to validate a set of previously optimised crushing sequences. More specifically, interparticle crushing sequences are carried out in a Piston-die testing equipment, where samples are sieved between each compression. The subsequent analysis of these results shows good correlation with model predictions, which combined with a comparative study between presented optimisation results and measured data from a real crusher indicate a significant potential for improvement. However, before redesigning crushers according to what is theoretically optimal, the resulting impact as well as the effects on the outcome of a crushing plant must be examined. Crushing plant simulations using the software PlantDesigner« are consequently performed. Models of existing crushers are altered, resulting in changed particle size distributions from some of the crushers in a crushing plant. Thence, it is concluded that significant gains can be made in terms of capacity, process yield and energy consumption.

Sep 13, 2010

Mine ore, reduced to minus 71/2 in. by primary crushers, is stockpiled. Size reduction of the reclaimed material by secondary and tertiary crushers is achieved in a closed circuit crushing and screening plant. Screen products of minus 30 mm plus 6 mm lump, and minus 6 mm fines are stockpiled by conveyor and stacker systems prior to rail despatch 10 port facilities at Dampier. Crusher settings, determined from experience, are closely maintained to obtain the desired lump/fines ratio. Chemical and sizing analyses from automatically taken samples are used to maintain product specifications. The beneficiation plant upgrades the fines product when this is necessary. The recorded wear life of individual plant components is the basis of a planned maintenance programme.

Jan 1, 1970

By S D. C Rabone

An elongate belt containing granodiorite stocks with associated stockwork molybdenum mineralisation in west Nelson is correlated with the I-type Separation Point Suite of mid Cretaceous age. Trace element characteristics of the 'Mo-granites', and the Separation Point Batholith strongly suggest a primitive, subcrustal origin for these granitoids, by partial melting of oceanic basaltic crust or upper mantle material in a subduction zone. They were emplaced in the upper crust without undergoing significant differentiation or contamination by sialic crust. Molybdenum, which is at levels of approximately 5 ppm in unaltered granite, is not significantly reduced in altered (but unmineralised) granite. This suggests the metallisation has a magmatic, subcrustal source and is not derived by hydrothermal leaching of upper crustal rocks or the granitic host rocks. Geochemistry of the 'Mo-granite' belt, in particular low K2O, calc-alkali to calcic Peacock Index, high Sr and TiO2, and low Rb, Nb and F, suggest classification as calcic granitoids similar to those which host porphyry copper deposits, indicating grades of mineralisation are likely to be low.

Jan 1, 1987

Treatment of the Siirt-Madenk÷y Ores by Flotation

Sep 13, 2010

Enhancement of Energy Efficiency in Fine Grinding of Copper Sulfide Minerals Using a Pilot-Scale Stirred Media Mill - IsaMill The mineral liberation size of run of mine ores has dramatically reduced over recent years. As a result, the demand for fine grinding which is the most energy-intensive form of grinding has markedly increased in the minerals industry. Furthermore, the fine grinding costs increase exponentially with decreasing product particle size. As a result of the increased energy requirement for fine grinding, it is desirable to optimise fine grinding processes such as stirred media milling (ie IsaMill) to enhance energy efficiency, throughput and the product fineness. In the present study, the influence of slurry rheology, grinding media type and grinding media-to-feed size ratio on energy efficiency in a pilot-scale IsaMill was investigated under certain industrially relevant pulp processing conditions. It was shown that a critical rheological state existed, below which the energy required to achieve an 80 per cent passing (ie P80) 20 ¦m product size was unaffected by shear rheology (ie apparent viscosity and shear yield stress) whilst above which the grinding energy required increased dramatically with increasing shear rheology. Colorado River sand (3.35 mm) showed higher energy efficiency than MT1 ceramic media (2.5 mm) for a target P80 of 20 ¦m in the solids concentration range of 38 to 55 per cent by weight, but the former experienced more than four times the wear rate of the later. The high wear rate of the Colorado River sand may be due to its much lower hardness. For feeds with an 80 per cent passing (ie F80) 70 to 110 ¦m, 2.0 or 2.5 mm MT1 media appeared to be more energy efficient than 3.5 mm MT1 media whilst a media-to-feed size ratio of 41 to 53 is applicable for ~50 ¦m (ie F80) feeds for efficient grinding.

Sep 13, 2010

The epithermal Au-Ag deposits of the Hauraki Goldfield have formed in the convergent plate margin setting of the Coromandel Volcanic Zone (CVZ). The deposits form as siliceous lodes in the upper parts of geothermal systems associated with andesitic and rhyolitic volcanism. Two types of low sulphidation epithermal mineralisation are recognised in these volcanic terranes. Vein deposits within the rhyolitic terrane in the east and south of the CVZ (Whitianga Province) are typified by Chalcedonic Silica-Adularia-Illite type mineralisation. The veins are hosted by both rhyolite-dacite volcanic rocks and the underlying andesitic basement. The mineralisation formed by episodic violent decompressional boiling of deeply circulating meteoric water, with some magmatic fluid contribution; this boiling was associated with hydraulic fracturing and hydrothermal eruptions in geothermal systems where the piezometric surface of the deep geothermal reservoir lay near-surface. Such episodic boiling provides chalcedonic veining, banding and brecciation textures, adularia stability, bladed calcite, and extreme loss of H2S gas from the fluid to cause major gold deposition.   Crystalline Quartz-Illite-(Adularia-Kaolinite) type mineralisation is widespread in the andesitic terrane forming the northern and western portions of the CVZ (Kuaotunu Province). There is a spatial association with weak mineralisation of the high sulphidation (Vuggy Silica-Alunite-Kaolinite-Illite) epithermal type and porphyry eu-Au type. Crystalline Quartz mineralisation is probably formed by the mixing of shallow acidic groundwaters with the ascending deep geothermal fluid in geothermal systems beneath andesitic stratovolcanoes. The piezometric surface to the deep geothermal reservoir in these systems is likely to lie at considerable depth, with acidic gases rising from the geothermal reservoir condensing within the overlying vadose zone. The cooling effect, oxidation and pH decrease accompanying mixing apparently overcomes the dilution effect, and results in quartz deposition, illite (and locally kaolinite) alteration, and precipitation of gold. A high level of base-metal sulphide precipitation also enhances gold deposition. Violent boiling of the mixing fluids may occur at local structural dilation sites, producing high grade "bonanza" gold mineralisation.

Jan 1, 1991

By D Craw

Previous studies of alluvial gold in Otago and Southland placer deposits have suggested a gold-mercury association for some deposits derived from Caples Terrane schist, whereas alluvial deposits on Torlesse Terrane basement typically have no mercury. A regional study of gold from Otago Schist vein deposits from both Caples and Torlesse Terranes has revealed the presence of both Au-Ag and Au-Ag-Hg alloys in both terranes. Au-Ag alloy (3 - 4 wt per cent Ag) is typical for gold found in most Torlesse vein deposits, and Au-Ag-Hg alloy (3 - 8 wt per cent Ag, 2 - 8 wt per cent Hg) is found in many Caples vein deposits. Au-Ag-Hg alloys are not exclusive to the Caples Terrane, however, as Au-Ag-Hg alloys with up to 4 wt per cent Hg are found in vein material from the Torlesse-hosted, HydeMacraes Shear Zone. In addition, not all Caples-hosted deposits have a gold-mercury association; gold grains from the Carrick and Invincible gold fields have no detectable mercury. The present study characterises gold compositions from various hard-rock vein deposits and has potential for determining placer-source relationships.

Jan 1, 2003

By A T. Job, M L. Edgar, P R. McAree

Characterising ores in-pit and in real-time presents a significant value opportunity for the mining industry. Hyperspectral imaging systems are proposed as an enabling technology to achieve this real-time characterisation. This paper considers the application of a hyperspectral imaging spectrometer mounted on a shovel. We define the performance requirements for such a spectrometer and associated subsystems during a typical dig-load cycle. The relatively high swing rotation speed of the shovel requires approximately video-rate exposure times to achieve good spatial resolution. We analyse a selection of components against these requirements and find that suitable commercial spectrometers, detectors and optics appear fit-for-purpose. Automated, real-time spectral classification systems are also available, with only relatively modest requirements for processing power. The paper argues that at near peak solar illumination, a system for field deployment at the required sensitivity is viable using only commercial off-the-shelf components.CITATION:Job, A T, Edgar, M L and McAree, P R, 2017. Real-time shovel-mounted coal or ore sensing, in Proceedings Iron Ore 2017, pp 397–406 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

A unique sluicing process for recovering tailing impounded in a valley was developed by Electrolytic Zinc Company of Australasia Ltd., West Coast Mines, Rosebery, Tasmania.Earthmoving equipment could not be used as most of the material to be recovered was semi-fluid. A conventional sluking method was also impracticable as there was no suitable working face from which the process could be commenced.Operations started from a flat surface, using special techniques for sinking through the tailing and establishing producing working faces as the sinking process continued.After about 2 years the bottom of the dam was reached and conventional sluicing methods could be used.

Jan 1, 1973

By N H. S Oliver

Five major veining events have been identified within the area surrounding the Mount Whaleback microplaty hematite deposit. These veining events can be directly correlated to the established deformation history of the Hamersley Province (Brown et al, in press). Vein formation temperatures of 203 to 231¦C have been obtained from primary fluid inclusions within veins which formed around the postulated time of ore formation. Preliminary proton induced x-ray emition (PIXE) analysis of these inclusions indicates KCl is the dominant salt species with varying levels of Ca, Fe, Ti, Mn present. It is suggested that some of these veins may have formed from feeder or effluent fluids from microplaty hematite ore formation.

Jan 1, 2002

A number of mineral deposits occur in close proximity to the Pacific plate fronts. Among these deposits are gold-silver and the base metal sulphide deposits of copper, zinc and lead. Gold deposits that commonly occur in these areas are of hydrothermal origin. Of these the epithermal deposits have attracted the attention of the exploration geologists as well as the metallurgists. One vital aspect of the activity of the geologists is the development of models for epithermal gold mineralisation in the Pacific Rim. These models can also be used by metallurgists for predicting gold extraction processes. This paper reviews the mineralogy, fineness and the host minerals of gold and examines the data in the light of gold mineralisation in the southwest Pacific Rim. The gold mineralisation models proposed for the Pacific Rim have been used to predict gold extraction processes suitable for the various mineralisation types. Discussed also are the mineralisation and treatment processes of some selected epithermal gold deposits and gold-rich porphyry copper deposits in Indonesia, Papua New Guinea, Solomon Islands, Fiji and New Zealand.

Jan 1, 1999

By R H. Sillitoe

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. Geological concepts are employed routinely in porphyry copper exploration at the area selection, prospect appraisal and deposit definition stages. Regional, district-scale, deposit-scale and laboratory-based concepts can all play a role, with the resulting porphyry copper models providing templates for the integration of geochemical and geophysical responses and interpretations. Of the 19 concepts and parameters selected for brief discussion, those relating to subdivision of porphyry intrusions, understanding of diverse and commonly complex alteration-mineralisation patterns and lithocap characterisation are undoubtedly the most influential in exploration. Several of them are of particular importance because of their role in promoting grade development. Additional belt-, district- and deposit-scale features are currently little used but hold promise, whereas others have less practical value but help in underpinning the evolving porphyry copper genetic model.CITATION:Sillitoe, R H, 2015. Recent advances in porphyry copper geology and their exploration utility , in Proceedings PACRIM 2015 Congress, pp 35–44 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By T Atchison

The Vale Ferro Carajßs S11D project in northern Brazil is based on the movement of unprecedented volumes of waste and ore for mobile in-pit crushing and conveying or ætrucklessÆ systems. In peak years, the system is intended to handle a combined 160 Mt of material.The planning and implementation of the first such system for Vale, in a remote greenfield site, utilising the services of a range of international study, design and supply partners has provided a unique set of technical and project delivery challenges. The lessons from these are of value to the industry as the trend to remote and high-volume operations continues.This paper describes the key features of the mining system and documents the challenges and mitigations for important technical, cultural and project delivery issues that have arisen. It is a combined description of the journey taken by both Vale (as owner) and SKM (as delivery partner) over the course of many years.CITATION:Atchison, T, 2013. Lessons from the S11D truckless mining project, in Proceedings Iron Ore 2013 , pp 177-184 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

Although the Diamond that is cut and polished and made up into an article of jewellery, is so well known, there are, comparatively speaking, very few outside the industry who know this beautiful crystal in the crude state, as turned out ofNature's laboratory, and the means employed in winning this precious stone.This article is written with the endeavour to give the reader some idea of the geological formations in which the Diamond occurs, and as it is reported that Diamonds have been found in Western Australia, as well as in other parts of the Australian Colonies, a few hints as to the means employed in working the ground in South Africa may be of use to those intending to prqsecute the search in this country. The general geological formation of the South African Diamond Fields is Lacustrine shales and sandstones, intersected by dykes of various eruptive rocks, varying considerably in their character. and in places vesicular in texture, the vesicules being more or less filled in with zeolites by permeating waters.