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By V Poizat

In different parts of the world the term epithermal is commonly used for a variety of deposit styles. Using the redox state of the ore-forming fluid (inferred from mineralogy and alteration), the metal assemblage of deposits, and other characteristics, at least five different styles of epithermal deposit can be distinguished. Most of these different deposit styles appear to be related to magmatic fluids, with differences resulting from different compositions of source magmas. The most common style of epithermal deposit (low-sulfidation gold-silver deposits associated with calc-alkaline volcanic rocks) remains the most difficult to explain; the metals in these deposits may be derived by basement leaching without magmatic input, or they may come from magmatic volatiles, with contaminated I-type or S-type magmas as the most likely source.

Jan 1, 1995

To the industrial geologist, as wen as to the general or historic geologist, the possession of a reliable key to the true order or sequence of the stratigraphy or position of the various upper rocky envelopes of the earth's crust, is, equally, a desideratum of the utmost importance. Of similar value to the two groups of students is the possession of facts which throw light upon the relationships which subsist between the puccessive rock formation of different countries, especially between countries lying close to each other, or within the same great geographical division.But there is necessarily a fundamental distinction which marks the respective limits of the field of observations of the industrial geologist, and the purely historic interest of the general geologist. The former has a more definite though less extensive scope. The scope of the latter is wide and indeterminate. In short, the observations of the industrial geologist are, 'from a commercial or economic point of view, of a more practical character, and are, therefore, intentionally restricted to the study of all geological questions which throw light upon the rocks which yield products of economic value and only include the study of the character and history of other rocks, in so far, as they afford aid to the more perfect comprehension of the best manner in which materials of economic value are likely to be sought, and the best means whereby these products may be secured for the material advantage of the community. The motive of the general geologist-in most cases-is a love of the study of some particular branch or province of the geological field, and the fascination of opening a new volume in nature's library, and the hope of extending the realm of knowledge, however slight, are often sufficient, as a motive, to enlist the energy and life's devotion of the true brethren of the hammer, irrespective of considerations regarding the commercial utility of the pursuit.

Experimental Study of Ore Characterisation Methods for AG/SAG Mills Mining companies have long recognised the importance of ore breakage characterisation in design and optimisation of their crushing and grinding circuits. In one of the industry standard methods relevant to AG/SAG milling, ore is characterised using mainly high energy single impact tests. However recent DEM studies have suggested that breakage in AG/SAG mills is mainly due to low energy repetitive (or multiple) collisions rather than single high energy impacts. Hence a study was initiated at the JKMRC to investigate the behaviour of ores under such conditions. Carefully designed experiments have been performed using two laboratory mill sizes (0.6 m and 1.1 m diameter) to mimic the reported low energy repetitive impact breakage under low load conditions. The breakage characterisation parameters derived from standard high energy single impact tests on the same ores was then used to predict the low energy repetitive impact breakage. Significant bias was found in the simulations which clearly warranted further investigation. The extensive experimental program which followed employed three separate methods: the JKRBT (JK Rotary Breakage Tester) for high energy single impact and low energy repetitive impacts, gravity drops for low energy repetitive impacts, and laboratory mills to provide an extended number of low energy repetitive impacts. The breakage energies associated with these experiments were accurately measured with a high speed video camera. Two breakage indices, the degree of breakage (t10) and the breakage probability (S) were used to describe the breakage test results. This paper summarises the major results from this experimental study, which has facilitated the development of a new breakage characterization method relevant to AG/SAG mill modelling.

Sep 13, 2010

Flotation Circuit Optimisation - Towards More Sustainable Practice

Sep 13, 2010

By Gupta R. C

Direct reduction of iron ore by solid reducing agents have been studied extensively and summarised by several authors (Otsuka and Kunii, 1969; Abraham and Ghosh, 1979; Frauhan, 1977; Rao, 1971; Kawasaki, Sanscainte and Walsh, 1962; Ghosh, 1970; Rao, 1979). While studying the reduction behaviour, it is generally agreed that the reduction occurs via gaseous intermediate, generated by carbon gasification reaction which involves mass transfer, heat transfer nucleation and growth, etc through a) reduction reaction occurring at solid reductant, and b) reduction reaction occurring at solid iron oxides, thus making the overall reduction process very complex in terms of clearly defining the reduction kinetics of the system. In addition to this, practical difficulties like correctness of reaction temperature, (Seaton, Foster and Velasco, 1983) difficulties in isothermal temperature studies of reduction, difficulties in monitoring the reduction process while using gaseous reductants and separation of reduction by volatile matter from overall reduction process make the reduction kinetics more complex (Misra).

Jan 1, 1999

By A R. Penney

Since mining-induced seismicity first became apparent at the Beaconsfield Gold Mine in 2002, there has been an ongoing program of geotechnical investigations to understand the phenomenon and allow for the development of strategies to manage the risks it posed to personnel, the business and the community at large. Studies resulting from a seismically induced rockfall on Anzac Day 2006 have been extensive, and have advanced the understanding and management of seismicity at the mine. Enhancement of the mineÆs seismic array, implementation of extensive monitoring of ground behaviour, improved ground support and reinforcement design, and ongoing numerical modelling provide a technical framework for the management of seismicity. In addition, extensive involvement of the workforce in risk assessment and the development of standard work procedures (SWPs), has contributed to a æbest practiceÆ approach to manage seismic hazards at the mine.

Jan 1, 2008

Western Australia has often been referred to as the fly-in, fly-out capital of the world. Fly-in, fly-out is a commonly used practice in Western Australia due to the geographic size and isolated location of the vast resource projects. In the State today, approximately half of all resource sector employees operate on a fly-in, fly-out basis, with a minority utilising drive-in, drive-out arrangements. fly-in, fly-out arrangements are generally beneficial from a sustainability perspective, delivering significant economic, social and environmental benefits to regional communities, the State and nation as a whole. Skills shortages and labour supply issues mean that the industry will be required to discover new ways of attracting and retaining employees, one of which is the adoption of fly-in, fly-out work journey arrangements. By 2015, the minerals sector in Australia will need to employ 70 000 more employees than it currently employs to achieve predicted increases in output. Of the 70 000 additional employees required, 42 000 will be required in Western Australia, almost 15 000 in Queensland and approximately 5000 in both New South Wales and South Australia. The fly-in, fly-out lifestyle as a preferred method of employment should be recognised as a valid lifestyle choice by all members of the community, offering a profound improvement in the quality of life for large numbers of employees and family members. It should be acknowledged that whilst fly-in, fly-out is a preferred option for many companies and their employees, individuals who make a choice to engage in fly-in, fly-out must balance the difficulties associated with the work û isolation and separation from family and friends û against the economic and lifestyle benefits that the work offers. This paper aims to illustrate the significant steps that the resources sector has taken to facilitate the fly-in, fly-out choice by ensuring that the commute option is a safe, attractive and manageable work journey arrangement.

Jan 1, 2008

By J Mercuri, S Dunford, P Rothman, E Bartsch, J Snyder, D Newton, R Maron, D Cirulis

The purpose of a mineral comminution circuit with a ball mill running in closed-loop with a hydrocyclone classification cluster is to feed the downstream process with the target particle size. Maintaining the optimal particle size in the flotation feed can significantly improve plant cash flow. In particular, reducing the amount of coarse material is often a major challenge. Existing instrumentation to provide particle size measurement is considered standard equipment in most modern concentrator plants. However, availability is often very low, mainly owing to high maintenance requirements of the analyser and associated sampling system.CiDRA Minerals Processing has developed two novel and robust technologies that address this challenge by providing high reliability and very low maintenance systems for on-line measurement of coarse material in the overflow of individual hydrocyclones. The first system is non-invasive and measures pebbles and rocks greater than 6 mm. This paper focuses on the second system, which is a ruggedized wetted sensor design with no moving parts and provides a real-time trend of the desired target grind size parameter, such as percentage above 150 micron.Both systems have simple robust designs and measure in the primary overflow stream of the individual hydrocyclone. Individual hydrocyclone measurement enables identification of poor performing hydrocyclones in addition to providing a representative measurement of the whole hydrocyclone cluster. The systems do not require sampling and associated sample transfer piping circuits that are prone to plugging, thus avoiding high maintenance requirements.The wetted sensor will be described in detail along with its implementation in a robust control scheme in a major copper concentrator in North America. Plant data shows very high availability, achieved with very low maintenance, has enabled improved process control, thereby maintaining throughput and ball mill target power while reducing grind size.CITATION:Cirulis, D, Dunford, S, Snyder, J, Bartsch, E, Rothman, P, Maron, R, Newton, D, O’Keefe, C and Mercuri, J, 2015. Process optimisation using real-time tracking of coarse material in individual cyclone overflow streams, in Proceedings MetPlant 2015, pp 93–109 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

Optimisation of the Performance of Flotation Circuits Using a Genetic Algorithm Oriented by Process-Based Rules

Sep 13, 2010

By G Liu

Seventy-nine gold deposits and prospects have been discovered in theJiamusi region of northeast China, and constitute one of the most important gold metallogenic belts in China. All these endogenic gold occurrences can be subdivided into three main deposit types: 1. porphyry related; 2. metamorphic-intrusive hosted, and 3. sediment-hosted deposit.   The first two types of gold deposit are spatially and temporally related to Mesozoic Yanshanian granitoid intrusions with hydrothermal activity channelled along crustal-scale fissures. The ultimate cause of the Yanshanian magmatism is considered to be the subduction of Pacific oceanic lithosphere beneath the Eurasian continent. In contrast, the chemical sediment-hosted deposit is typified by the Dongfengshan gold deposit, and genetically related to Proterozoic sedimentation and Mesozoic igneous activities.

Jan 1, 1995

By S Vianna, K Caldwell, R Silva, T Olson, D Bell

Studies to enhance the FLSmidth forced air machine through changes in the design, showed important improvements through changes in the number of Rotor blades, stator designs, rotor air distribution and other designs features. The main outcomes from this study highlighted that increasing the number of rotor blades increased the selectivity while decreasing power requirements while stators with slots have better results in terms of recovery, flotation efficiency and selectivity than without slots.Also the rotor air distribution makes a difference in the design when comparing different distribution criteria whilst keeping all features of shape and number of blades etc constant. At the most efficient rotor air distribution design, copper recovery reached one of the highest values while keeping good selectivity. The possible explanation for that is the increase in the pump capacity indicated by the increase in the specific power.It was seen as significant that reduction in specific power for some designs tested compared with the then current standard design had an average of 30% less power consumption.As a result, FLSmidth was able to identify new designs that decreased power and improved recovery, as well as, identifying some designs that specifically improved fine and/or coarse particle recovery.CITATION:Silva, R, Caldwell, K, Bell, D, Olson, T and Vianna, S, 2013. FLSmidth flotation developments - Dorr Oliver machines, in Proceedings MetPlant 2013 , pp 413-430 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 15, 2013

The mineral composition and microtextures of a cubanite-rich sulphide ore are described and cubanite breakdown textures are illustrated. The occurrence of cubanite in macroscopic dimensions is featured.The origin of the ore is tentatively related to a composite ore fluid arising initially from an ultramalic source and extracting some metal components from an older granite mass along the margin of which the serpentine was emplaced. Some alternative possibilities as to origin are also mentioned.

Jan 1, 1969

ALTHOUGH great progress has been made in flotation of the Broken Hill silver-lead-zinc ores, no paper dealing with this subject has been presented to the members of the Institute since James Hebbard's valuable contribution in 1913. Almost every discovery or development in the history of flotation has formed the basis 6f a patent, and but few experimentalists have overlooked the fact that their investigations might lead to the establishment of a patentable process. This, together with the aftermath of patent litigation, naturally resulted in secrecy being maintained in matters appertaining to the art, and the industry as a whole has consequently suffered considerably. Much valuable time has been wasted through numbers ofmen repeating work along certain lines, which, unknown to them, had already been thoroughly exhausted by others, whereas a lot of this would have been avoided by a freer interchange of information amongst those directly concerned. Owing to differences in the ore treated and the various applications of flotation concentration in relation to gravity methods, the flotation problems of the various mines differ considerably. This, together with the secrecy previously referred to, hasresulted in the development of numerous systems and machines, most of which would appear, to the casual observer, to comprise separate and distinct processes. The author has endeavoured to show how much these processes have in common with one another, and, at the same time, has tried to convey some general ideas on flotation to those members of the Institute who are not directly associated with this branch of concentration.

Jan 1, 1919

By P E. H Gregg, D Horne, R B. Stewart, N Bolan

The Tui mine site is situated on the NW flank of Mt. Te Aroha, at approximately 400 m altitude. During underground mining operations two lead-copper-zinc ore bodies were exploited and processed on site. The legacy of the mining operation is a barren dam containing over 100 000 mm of sulphide-rich tailings. The Tui mine site is arguably the worst case of environmental degradation resulting from past mining activity inNew Zealand. Although the impacted area (approximately 4 ha) is extremely small by international standards, acid mine drainage (AMD) emanating from the abandoned tailings dam and mine adits has severely contaminated local streams and prevented natural plant recolonisation of the site for more than 20 years.   The suitability of the tailings as a potential plant growth medium was assessed with the end view of revegetating the tailings dam and alleviating AMD. This paper outlines characterisation work conducted on the tailings and summarises preliminary results from plant growth trials. The tailings contain up to 5% Fe, 1.15 % Pb, and 0.45% Cu in the form of sulphide minerals. The distribution of heavy metals, sulphate and total sulphur with depth indicates that the top 200 - 300 mm of the tailings have been extensively weathered since their deposition. The oxidation of sulphide minerals, particularly pyrite (FeS2 ) has reduced the pH of the tailings to nearly 2 in places. Below 300 mm the sulphide minerals are largely unweathered and the theoretical acid generating potential of the tailings exceeds 170 Mg CaCO3/1000 Mg tailings at certain depths. Plant growth trials were conducted to study the effects of lime and organic matter addition on the establishment of vegetation on the Tui mine tailings. Several plant species were assessed including some cultivars bred for their tolerance of heavy metals.

Jan 1, 1995

By Matters, R T, Coldham, Slee, J C, R J, Wallman

The Committee desires to thank the managers of the various mines along the line of lode for their hearty co-operation in its labours. It would also extend thanks to Messrs J C Moulden, Howchin, Twelvetrees, and the West Australian Geological Surveyfor various information; to Messrs J G Dreyer, S Pope, T Read, P Moncrieff, R Williams, and W J Rose for analyses; and to a number of local gentlemen for advice and help. Professor Skeats, of Melbourne University, gave much valued assistance in petrology, and Mr Herbert Lavers kindly undertook the study of the garnets.INTRODUCTIONThe famous Broken Hill lode is situated in a low range of hills, the Barrier Ranges, near the western border of New South Wales. It has been worked since 1884-fust for silver, then for silver and lead, and at present for lead, silver, and zinc...

Jan 1, 1910

By J Widjaja, E Hermawan, M Muharam, L Damanik

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. The island of Java lies within the Sunda-Banda magmatic arc, which is characterised by multiple phases of volcanic activity and extensive compressional deformation. Along this zone, significant gold and copper mineralisation occurs, including some of the world’s largest deposits. In West Java, epithermal gold mineralisation is typically located in a series of extensional and strike-slip faults that cut Miocene to Pliocene volcanic rocks. These are all low-sulfidation, epithermal, vein-stockwork-style deposits developed in Miocene to Pliocene calc-alkaline volcanic rocks, which have been intruded by shallow-level plutons.This paper discusses an example of epithermal mineralisation at Mt Subang, West Java. Gold mineralisation was originally identified from stream sediment, panned concentrate and rock geochemistry sampling in the early 1990s. Geophysical surveys (magnetics and induced polarisation resistivity/chargeability), trenching, pitting and diamond hole drilling has subsequently revealed silicified-quartz vein epithermal gold mineralisation hosted within fault structures. It is clear that these structures acted as hydrothermal fluid pathways leading to the development of mineralised offshoots along north–south extensional and en-echelon arrays of north-east–south-west and transtensional faults. A number of vertical offshoots also occur in flexures and fault jogs. Post-mineral faulting has subsequently dissected and offset a number of the offshoots. Therefore, a detailed knowledge of structure and fault kinematics and displacement magnitudes is required in order to understand the geometry and continuity of mineralisation across major structures and maximise the resource potential. A range of exploration targets were modelled, indicating a minimum and maximum of 0.2 and 1.8 Moz of gold respectively.CITATION:Cunningham, M J M, Muharam, M, Damanik, L, Hermawan, E and Widjaja, J, 2015. Structural controls on the localisation of low-sulfidation epithermal mineralisation in West Java, Indonesia , in Proceedings PACRIM 2015 Congress, pp 227–234 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

Kalgoorlie is the main mining centre of the Western Australian Goldfields. Its famous Golden Mile' has been noted for the exceptional width and richness of its goldtelluride lodes. Since the mid-1890s production on the major mines has been maintained practically continuously.Rich ore, though not as plentiful or as rich as formerly, is still (1948) being mined in places. Unexplored areas still remain within the main auriferous belt which offer reasonable chances of success with intensive exploration.Much detailed information has accumulated in recent years through the geological mapping of underground workings by some of the larger mining companies. The purpose of this paper is to correlate observations made in most of the accessible old and recent workings in the mines of the Lake View and Star group and elsewhere.GENERAL GEOLOGYRock TypesThe rock formations are:-1. Fine-grained (older) greenstones, locally referred to as calc schists. There were originally pillow lavas and other flow rocks of basic composition, now extensively chloritised and/or carbonated. Pillows and fragmental flow- tops are recognisable. Intercalated with flows near the top of the series are several beds of sediments.2. Graphitic slates and other more arenaceous sediments.Although referred to as slates, they are rarely more than well-bedded shales with poorly developed fracture cleavage:Thick bands of felsitic rock are found in places.

Jan 1, 1952

Drill cores from Section 62, New Broken Hill Consolidated Ltd., were used to study the petrology of rocks associated with the zinc lode. The distribution of the rock types in relation to the lode structure was determined. The distribution of the gahnite-bearing rocks was shown to be only partly conformable with the structure.It was concluded that large scale metasomatism was not widespread, that the rocks associated with the lode (except, perhaps, the quartz-gahnite-garnet rocks) were formed by metamorphism of sediments, and that rocks and lode were contemporaneously metamorphosed.INTRODUCTIONThis investigation was undertaken in order to study the rock types associated with the zinc lode of the Broken Hill orebody, and their relationship to the structure of the ore horizons. The work was confined almost entirely to the laboratory, and is therefore limited in its scope. It is hoped, however, that the information gained may throw some new light on the genesis of the lode.Certain inferences which are drawn from this work are at variance with the ideas of a number of earlier workers.In particular, the idea of large scale metasomatism developing many of the rocks associated with the lode, especially those containing manganese, is questioned. On the contrary, the rocks associated with the lode are more simply explained as highly metamorphosed sediments, in some cases modified by water introduced from surrounding rocks into zones of strong folding and faulting. As a corollary, a metamorphicsedimentary origin for the lode material, either as a concentrated sulphide deposit, or somewhat disseminated...

Jan 1, 1961

By J Kelly, C Kelsey

The Autogenous Kelsey Axial Displacement (KAD) mill is essentially a short retention time centrifugal mill, designed to effectively harness extraordinarily high concentrations of input energy for efficient particle size reduction. The mill which has an operating duty band extending from primary to ultra-fine also has the unique capacity to generate fine and ultra-fine products from single stage size reductions of either coarse or fine mineral feeds, in both wet or dry operating modes. This paper covers developments following a recent optimisation programme which confirmed that mill shell speed and the velocity differential between the shell and the rotating internal disc assembly tips could be optimised in relation to specific energy for a given feed rate and feed size providing the product size remains constant. Subsequent test-work further demonstrated the versatility of the mill with duties ranging from the removal of surface contamination associated with heavy mineral concentrate particles to the production of premium ultra-fine talc, from a single stage of size reduction. Open circuit grinding of a rougher gravity concentrate to liberate gold ahead of leaching also highlighted the scope for the application of low cost KAD milling for a range of hydrometallurgical feed preparation duties, which involve fine and ultra-fine grinding.CITATION:Kelly, J and Kelsey, C, 2013. Advanced media-free fine and ultra-fine grinding - The Kelsey axial displacement mill, in Proceedings MetPlant 2013 , pp 152-161 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 15, 2013

To optimise the haulage of the large tonnages produced from stopes in this high production gold mine, an ore pass and feeder system was introduced. This ore pass was designed and developed in 2006 and the plate feeder installed and commissioned soon after. Cavity Monitoring Surveys (CMS) have been undertaken of the ore pass since it was commissioned. The original thickness that was surveyed of the pillar between the ore pass and decline in 2006 was approximated to be 19 m. Throughout its use large blocks of rock were reporting at the plate feeder. This was the first indication that the ore pass was failing somewhere between the tipping level of the 9410 level and the plate feeder at the 9330. Even so CMS surveys were not taken systematically to firstly identify the area of failure or for monitoring. In August 2008 after implementing management systems, large blocks were still reporting to the plate feeder. The decision was made to empty the pass enough to carry out a CMS survey of the area. Subsequently it was discovered that the area of failure was between the decline and ore pass and that since the first survey the pillar thickness had been reduced to approximately 9.7 m. Further management controls were put in place to slow movement of the material and to limit the use of the 9410 tipping level, but this did not alleviate the rate of failure entirely. The results of an initial inelastic numerical model indicated that most of the pillar was damaged and that failure into the decline likely if no changes were made. The numerical modelling predicted that even if material was no longer passing through the ore pass interaction between the voids was unavoidable and would most likely result in instability. The ore pass and plate feeder are an integral part of the haulage system for the remaining life-of-mnie. Two solutions were sought to firstly reinforce and stabilise the pillar between the ore pass and decline and secondly to rehabilitate the ore pass or find an alternate design that could still utilise the plate feeder. This paper summarises the analysis and resulting rehabilitation that was used to accomplish this.

Nov 25, 2010