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Australia is not capitalizing on the raw gems and precious minerals that it produces in abundance. In particular, there is an unrealised value for diamonds due to lack of processing after mining. Australia could enhance the value of its raw jewellery products by developing and integrated jewellery industry. For instance, initiation of a diamond industry would require training programmes to educate people in the requisite skills, such as diamond sorting, cleaving, sawing, bruting and polishing. Equally important would be the training of people in design jewellery, manufacturing, and appropriate diamond grading and sales techniques. Future technological advances in diamond processing will decide where the major diamond processing centres of the world will be. Australia, for a relatively small investment, could develop a highly productive diamond processing capacity using the new technology available. Australia's geographical position, and advanced banking and communication facilities provide the potential for this country to become a major trading centre for diamonds. KEYWORDS: Argyle Diamond Mine, Diamonds, Diamond Production, Diamond Sorting, Jewellery Industry

Jan 1, 1989

Since the end of World War n, many important developments have taken place in the investigation of the phenomenon of brittle fracture in mild steel. Fractures in certain classes of welded ships, in welded bridges, penstocks, etc., focussed a great deal of attention on the interrelationships of design factors, service conditions, and steel quality on the generation of catastrophic failures.Much publicity has been given these major failures, and there is perhaps a tendency to forget that mild steel, under certain conditions, as well known to behave in a brittle fashion in a wide range of everyday engineering applications.For instance, many who are connected with the haulage and lifting of heavy loads will be familiar with the bright "crystalline" fractures of crane hooks and chains which sometimes follow sudden jarring; those concerned with the heavy pressing and shaping of steel plate will not be unaware that at times sudden brittle splits or tears will develop for no obvious reason in, say, rolled pipes or in dishings.In fact it will be evident upon reflection that in many cases the conditions which mild steel has to withstand during processing into an engineering part or structure are more severe than those it wili be called upon to endure during service. In this sense brittle fractu;res in mild steel are much more frequent than are commonly supposed.Two modes of fracture are now generally recognised to occur in metals, namely, shear and cleavage. The latter manifests itself by the so-called "crystalline" fracture (here...

Jan 1, 1954

By B Bamford

High speed diamond cutting has extensive applications in civil and mining engineering. A project involving the diamond sawing of black granite is investigating the nature of the diamond cutting process. A sawing machine was devised to adjust the cutting load and measure cutting speed. Cuttings were collected for size distribution analysis. The surface produced by interaction between diamond. grits and the rock was subjected to microscopic investigation. Increasing load prompts the proportional increase in the cutting rate. But the mean size of cuttings shows little change. The photomicrographs of the cutting tracks indicate neither patterns of crack formation nor signs of the ductile behaviour of the rock. A diamond cutting model for hard rock is formulated on these observations. Diamond cutting is a process of surface failure, which advances in four stages. The polycrystalline characteristics of a hard rock and the action of high-speed diamond grits guarantee the creation of crack nuclei which develop into cracks in various directions. This network crisscrossing cracks enable the stripping of this surface layer from the rock.

Jan 1, 1992

By Mukhopadhaya K. K, Cory A. H

The concept of using travelling magnetic fields created by linear motors was stimulated by Laithwaite who advanced ideas on motors with shaded poles (Laithwaite, 1968), rack and pinion motors (Laithwaite, 1970) as well as low speed, brushless motors and three dimensional motors (Laithwaite, 1973a and 1973b).Sudan (1963) and Sundberg (1969) had applied the concept to metallurgical processes. However, the use of travelling magnetic fields has not been used widely to produce conditions for the separation of magnetic from non-magnetic minera1s or even magnetic materials from non-magnetic materials, although some attempts were made by McCarthy (1922), Davis (1934), Dean, Gottschalk and Davis (1934) and Gottschalk (1934).Laithwaite (1973, a) while working with linear motors made suggestions for designing separators and in the work described here, the observations of Laithwaite and others are extended to determine the characteristics of the motor with a view to using it as a magnetic separator.

Jan 1, 1980

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 D Craw, G Eis

Late Cretaceous Blue Spur Conglomerate preserved as isolated remnants at Gabriels Gully, Weatherstones, Forsyth, Waitahuna Gully and Adams Flat was deposited during the intiation and early stages of extensional movement on the Tuapeka Fault zone at each locality. The deposits represent successive courses of a single fluvial system flowing across the Tuapeka Fault zone from the up-thrown (northeast) block. Each course, beginning with the channel at Gabriels Gully, was abandoned as a result of uplift-induced defeated antecedence in favour of a new course farther to the southeast around the southeast-propagating tip of the Tuapeka Fault zone. Schist and quartz in the conglomerate was derived ultimately from schistose rocks northeast of the Tuapeka Fault zone. Caples Terrane greywacke detritus in the middle and upper beds of the conglomerate was probably recycled from pre-existing sedimentary cover on the up-thrown block, following initiation of uplift on the Tuapeka Fault zone at each locality. Most of the gold is derived from vein sources in Otago Schist rocks to the north, and/or associated placers. Hydrothermal veins at Waipori, Hindon, Barewood, and Macraes are the most likely primary sources. There is no evidence to support previous interpretations of deposition by river systems flowing from the southwest, or axially along the Tuapeka Fault zone from northwest to southeast. High gold grades within Blue Spur Conglomerate should have a linear trend more or less similar to the orientation of the host channels, but are likely to drop off rapidly to the southwest. Extensions of the conglomerate-filled channels are unlikely to be preserved, but there is a strong probability that younger placers recycled from the former channels exist.

Jan 1, 1999

By L Spencer, H Zwingmann, I Graham, D Cendon, B Kelly, D Burkett, F Lau, P Lennox

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. The Kulumadau deposit represents an intermediate-sulfidation epithermal gold deposit (3.8 Mt at 2.3 g/t, Ag:Au = 1). Mineralisation is primarily confined to hydrothermal breccias within pre-existing fault zones, where it is disseminated throughout a hydrothermal matrix comprising chlorite-quartz-adularia-illite-I/S clays-calcite-pyrite. The host sequence represents numerous mid-Miocene pyroclastic flow eruptions within a tectonically active emergent shallow marine to subaerial depositional setting. Subsequent growth faulting was responsible for debris avalanches, which were subsequently cut by reverse faults. Faults were exploited by hydrothermal fluids, with the heightened porosity at the juncture between faults and debris material facilitating boiling of the ore constituents. Fluid inclusion studies suggest that fluid mixing between meteoric fluids and magmatic fluids, accompanied by boiling, were the primary mechanisms for gold deposition. The occurrence of anhydrite/gypsum as late-stage veins and their sulfur and oxygen isotopic values indicate post-mineralisation mixing of sea water with hydrothermal fluids.CITATION:Burkett, D, Graham, I, Spencer, L, Lennox, P, Cohen, D, Zwingmann, H, Lau, F, Kelly, B and Cendon, D, 2015. The Kulumadau epithermal breccia-hosted gold deposit, Woodlark Island, Papua New Guinea, in Proceedings PACRIM 2015 Congress, pp 205–212 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By P O. Koons, R J. Norris, S C. Cox

 The Southern Alps is an active oblique collisional zone which has a characteristic wedge-shaped geometry above a low-angle ductile shear zone. The Main Divide region is a relatively low strain zone above this ductile shear zone, and is _deforming principally along steeply dipping strike-slip faults. Extensional fractures are common at a high angle to the regional structural trend. These steeply dipping structures act as conduits for gold-bearing fluids from depth, and small mesothermal gold deposits have formed at several structural levels including the near-surface region. Gold has also been deposited in a meteoricmetamorphic fluid mixing zone near a conductive thermal anomaly on the western slopes of the mountains. These various gold deposits and their well-constrained structural and tectonic settings can be used as analogues for larger, deeper-eroded mesothermal gold deposits in the Mesozoic Otago Schist belt. High level Miocene veins in NW Otago have formed beneath the main divide of the initiating Southern Alps. Late metamorphic gold-bearing veins formed as fluid escaped from the ductile-deforming crustal root beneath Mesozoic mountains.  

Jan 1, 1997

The Ministry of Economic Development has as its slogan æTogether making the differenceÆ. The Ministry is required to work in partnership with the private sector, local authorities, Maori economic entities, trade unions and community groups to transform New Zealand's industrial and economic base. The Government is seeking to achieve sustainable and balanced economic development by: being more actively involved in economic management; working in partnership with the public and private sector and with worker and business interests; focusing on adding value in industries (including primary industries) with long term potential; and bringing the tools of economic policy together in a coordinated way. The Ministry, particularly through its operating group Crown Minerals, is committed to working with industry to achieve mutual goals and to obtain continuing investment in minerals and coal exploration and mining and an active New Zealand minerals industry.

Jan 1, 2000

By Z Chang, S A. Mrozek

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. Antamina, Peru is the largest Cu-Zn skarn deposit in the world. Skarn mineralisation is focused around a multiphase Miocene intrusive complex comprising at least eight distinct phases identified by cross-cutting relationships, including truncated veins, xenoliths and chilled margins. Skarn alteration and mineralisation, as observed in drill core, remain open at depths exceeding 2.2 vertical kilometres.Porphyry intrusions occur as four major phases with subphases (from oldest to youngest): P1 (a, b), P2 (a, b), P3 (a, b) and two dykes of uncertain timing named Oscarina-1 and Oscarina-2. P1a is a hornblende-biotite quartz diorite porphyry with pervasive K-alteration, local endoskarn and 30–40 per cent sheeted quartz veins, all of which obscure original igneous textures. P1b dacite porphyry is a minor unit with <10 per cent phenocrysts and <3 per cent quartz veins. P1b cuts P1a; P2 dykes cut both units. P2a porphyritic biotite quartz monzonite contains K-feldspar megacrysts up to 4 cm long, local K-alteration and 2–80 per cent quartz stockwork veins. P2b biotite monzonite porphyry contains approximately 50 per cent phenocrysts and typically <10 per cent quartz veins. P3a (brown groundmass porphyry) and P3b (coarse phenocryst porphyry) are minor in volume and extent, and both cut P2 bodies. Oscarina dykes comprise two separate but parallel bodies. Oscarina-1 is a feldspar-phyric rhyolite porphyry, while Oscarina-2 is an intensely chloritised andesite porphyry. Oscarina-1 has a U-Pb (laser ablation inductively coupled mass spectrometry (LA-ICP-MS)) age of 10.1 ± 0.1 Ma, whereas P2 U-Pb zircon ages (LA-ICP-MS) range from 10.0 ± 0.2 Ma to 9.9 ± 0.3 Ma.All the intrusive phases contain quartz veins, with P1a and P2a having the most intensive K-alteration and most abundant quartz veins ± endoskarns. Each phase may have contributed to mineralisation at the right depths and within favourable wall rocks (ie marble) during uplift of the Antamina structural block. Therefore, a model of multiple intrusions during continuous uplift explains the vertically extensive (>2.2 km) skarn and mineralisation at Antamina.CITATION:Mrozek, S A, Chang, Z and Meinert, L D, 2015. A model for the intrusive sequence and Cu-Zn skarn formation at the Antamina deposit, Peru , in Proceedings PACRIM 2015 Congress, pp 423–430 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

Building the Unified Comminution Model The Unified Comminution Model (UCM) was formulated with the vision of bringing all comminution models onto a common base. The structure of the model relies on knowledge of the mechanical environment in the comminution devices to predict the modes and rates of collision in a device. A detailed understanding of the breakage modes and an ability to correctly test these modes for the ores in question is then required to feed into the UCM. A model structure has been developed that has the capability of dealing with multiple modes of breakage, such as low energy impact surface damage, chipping, sliding abrasion, cumulative impact body breakage and the transition of rock between modes. A critical review is presented on the shortcomings and limitations of utilising the discrete element method (DEM) to provide the mechanical environments. The assumptions and applicability of utilising DEM in milling models are presented and proposed routes to building a realistic mechanistic model are proposed. Based on this more realistic measures of collision energy have been derived from the DEM simulations, which better mimic the real breakage tests. Generic forms of the collision energy distributions have been observed and developed into functional forms for use in the simulation environment. The method of application of this model to a pilot SAG mill is presented.

Sep 13, 2010

By P M. Ashley, M Muller

Massive sulphide ZnPbCuAg deposits in the Halls Peak district of north-eastern NSW are of the submarine volcanogenic type. They occur as a number of small lenses enclosed in shale and epiclastic rocks, in association with felsic volcanics of early Permian age. The deposits crop out in steep terrain near the eastern edge of the New England plateau. Local relief of 700 m and slopes up to 50¦, coupled with an average annual rainfall of about 1000 mm has led to local severe land sliding in previously mined areas. Mining from the 1890s to the 1960s has also resulted in unconstrained drainage of heavy metal-bearing acid waters and physical dispersion of finer grained metalliferous sediments into the Chandler River. Waters emanating from the main landslide area, from underground workings and draining scattered unconfined stockpiles of massive sulphide ore have pH values of 3 to 4 and contain elevated contents of Zn, Cu, Pb, Cd and Fe. Chemical mobility of heavy metals into streams occurs under low pH conditions with Zn exhibiting the greatest dispersion. Increasing pH conditions downstream cause precipitation of Fe phases and coprecipitation of heavy metals. Physical dispersion of secondary metal-bearing minerals into the surrounding creeks results in wt% levels of Cu, Pb and Zn in the stream sediments thereby exceeding the regional background values by one to three orders of magnitude. Areas disturbed by mining are characterised by lack of vegetation, biomagnification of heavy metals into algae and lower plants, and partial recolonisation by metal-tolerant grass species (Snow Grass, Poa sieberana; Blady Grass, Lomandra longifolia). Rehabilitation measures will have to include landslide stabilisation, impervious sealing or removal of sulphidic materials, import of topsoil and revegetation by metal-tolerant, slow-growing native grass and shrub species.

Jan 1, 1995

IT has often been stated in the past that the materials known as inert fillers were merely adulterants nsed in the manufacture of paint, and that their purpose was to cheapen paints made from more expensive pigments, such as zinc oxide or white lead. In recent years, however, practical tests in various parts of the world have proved that many of the inert fillers, when used with wisdom, possess very definite and advantageous properties.Another oft-repeated statement which had a far-reaching effect in the past, and which is not without influence to-day, is that the very best paint must always be made from a pure pigment, without admixture with either a fellow pigment or an inert filler. Both or either of these statements may be true in a few isolated instances, but for the vast majority of ordinary painting conditions there is an abundance of experimental evidence to prove that neither is true.With the desire to further investigate these points and po 'determine the best combination of pigments and fillers for use as an outside white paint on plant buildings, a number of panels were prepared in the laboratory of this company.

Jan 1, 1924

Geotechnical input is interwoven into the mining process at George Fisher South Mine from the planning and design of working areas to the closure of worked out areas and maintenance of life of mine and long term excavations. The methodology used consists of a mixture of application of established theoretical principles and guidelines derived from successful historical experience. In the development stage, including long term infrastructure excavations, the process takes into account the expected life of the excavation, usage and expected stress changes during its life span. On the stoping stage, the design process takes into account the local rock mass conditions, geological structure setting and previous experience in a particular orebody. Due to the high variation in age of currently used excavations, a rolling monitoring and risk assessment process for long term and life of mine excavations and infrastructure is maintained. This paper has as an output the process that must be followed to ensure an excavation on the highly dynamic mining environment at George Fisher South Mine is blasted and maintained in compliance with applicably commonly accepted safety and industry requirements.

Nov 25, 2010

By D Craw, I M. Turnbull, R J. Norris, N Mortimer

The Otago Schist is being subdivided on a regional scale into structurally, metamorphically and lithologically distinct blocks. Differences between blocks are subtle, and difficult to map in the field. Boundaries are late-metamorphic or immediately post-metamorphic in origin, and are different from later brittle faults which disrupt the schist. Mapping of late-post-metamorphic structural discontinuities has direct application for basic grassroots exploration in the Otago Schist. The mineralised (and currently mined) Hyde-Macraes Shear Zone forms a regional scale boundary between a block dominated by politic schist and a block with massive psammitic schist, pelitic schist, and minor greenschist and chert. The HMSZ forms a metamorphic discontinuity, with garnet and biotite in the underlying schist, and neither index minerals apparent in the overlying schist. The HMSZ is also a structural boundary between domains with differing lineation orientations. The HMSZ can not yet be traced along strike to the northwest to the Rock and Pillar Range, where the only major discontinuities recognised are the Caples-Torlesse boundary and a normal fault separating low grade from high grade schist. Structural and lithological discontinuities in the Dunstan Range break the range up into distinct structural blocks, two of which are separated by the gold-mineralised Rise and Shine Shear Zone.

Jan 1, 1999

The small scale alluvial gold mining industry in Papua New Guinea (PNG) is c.irrently the only form of small scale mining carried out in this country. It already contributes significantly to the economy with current production estimated at 2 000-2 500kg per year. Until recently, small scale alluvial gold mining has been confined to simple panning and sluicing of high grade alluvial and colluvial deposits. Traditionally the small scale miner in PNG has only worked gravels with gold grades in excess of 500mg/m3. Grades of this order are required to justify the hard physical labour involved ~n hand operated small scale mining methods. .he introduction of higher throughput technologies such as trommels fed by hydraulic excavators has the effect of altering what constitutes an economically viable deposit. Mechanised techniques allow for the consideration of grades of almost half that level. The potential and opportunities for utilising this type of small scale mechanised mining in PNG are enormous with large areas of ground with gold grades running in excess of 250mg/m3 and often up to 2000mg/m3 throughout the country. An assessment of the current operating economics of this technology in the PNG context is the principal objective of this paper. Small to medium scale mechanised mining can potentially contribute significantly to the PNG economy particularly as it lies within the react-, of many PNG businessmen. Its potential is currently somewhat limited by a general lack of infrastructure and is also constrained by socio-political factors.

Jan 1, 1991

By Giannini M

Of the optimization techniques proposed in determining the optimum open pit limits, dynamic programming and graph theory have proved most successful. However, publications on these two methods lack a certain amount of rigour and clarity in exposition. Certain ideas in the methods have been clarified and additional features introduced in order to make them more sensitive to practical applications. A case study in the form of an application of these ideas on data from a producing mine is presented and discussed.

Jan 1, 1986

The Taupo Volcanic Zone inNew Zealand and the Philippine Mobile Belt in the Philippines are characterized by active subduction, active volcanism and high seismicity. The main factors affecting characteristics of geothermal systems in both countries are: tectonic setting, source magmas, maturity of the systems, and depth to the degassing magma body. Within New Zealand, geothermal systems are grouped into arc- and rift-type. Fluids in arc-type systems contain high amounts of volatiles (<20%), with high CO2/Cl, CO2/He, and N2/Ar ratios. Mantle-type volatiles predominate in rift-type systems. Philippine geothermal systems are largely arc-type, the topography is rugged, leading to the separation of water and vapour upflows, as opposed to the overlap found in New Zealand. The relatively shallow depths of degassing magma bodies in the Philippines results in steeper geochemical gradients, leading to higher proportions of arc-type magmatic water (>40%) and higher Cl contents (3000 - 10 000 mg/kg), Maximum temperatures are also higher, reaching up to >400¦C. Arc-type alteration assemblages in New Zealand and the Philippines are similar. Because Philippine geothermal systems are less mature, have higher temperatures and steeper geochemical gradients than New Zealand ones, advanced argillization is more widespread occurring down to depths of 2000 m. Mineral phases are more varied due to the active input of magmatic waters and the formation of vapor conditions at depth, forming P04-, B-, Li-, Ce-, F-, and Cl-bearing minerals at high temperatures. In the Philippines, high temperature magmatic-hydrothermal to contact metamorphic assemblages containing biotite, amphiboles and pyroxenes are relatively common, but rare in New Zealand.

Jan 1, 1995

Estimating Breakage of Fine Ore Particles by Media in a Small Ball Mill Using DEM

Sep 13, 2010

It is no longer satisfactory to assess the value of a coking coal on its intrinsic properties alone; its value depends upon its behaviour as a component in a blend. No single test can be used to make this assessment, it can only be made by carrying out a suite of tests. The quality parameters which are considered desirable, and which have widespread acceptance, have been discussed and their application to the blending of coals from New South Wales and New Zealand has been reported and discussed. Blending can be utilised to offset deficiencies, or capitalise on advantages, of the individual coals making up a blend. Coals can be blended, which alone are poorly, Coking, but which have compensating features. Blending also allows better exploitation of coking coal reserves. Several applications of blending have been reviewed with regard to coal producers and exporters, as well as coal users. The possibility of extracting a coking coal fraction from fuel coals is discussed. Blending systems and the coking of coal are also briefly reviewed.

Jan 1, 1971