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By R F. G Phelps, C J. S Sangster, G S. C

Narrow vein metalliferous mining in the UK has a long history, but there are only two small gold operations at present (Clogau and Gwynfynydd). Four further gold properties are at various stages of evaluation (Calliachar, Cononish, Curraghinalt and Maestryfer). The South Crofty tin mine closed earlier in the year. Narrow veins are exploited underground and are challenging to evaluate because of their geologically variable nature. They are generally less than 3 m wide, discordant, of variable dip (

Jan 1, 1998

By A. J. MOORE

When the writer first saw the square-set timbering, he was at once impressed with the fact that the frames made by the sets, along the lode and across it, were composed of panels with rectangular openings, and it was puzzling to understand howsuch a collapsible construction could resist pressure that came unevenly on it. Later he learnt that the sets did not satisfactorily resist such pressure, but mullock filling had, to a great extent, to undertake this duty for them. So it appeared that the setswere practically an expensive scaffolding, enabling the miners to work in the face and carry the stope forward, till the filling was put in behind them to take the pressure of the roof and sides of the excavation. Of course some of the pressure is takenby the sets, but this is because "the set timbers prevent the filling being done perfectly; if it were practicable to remove the sets before filling, the filling by itself would more effectively support the back and wall, than do the combined sets andmullock. On the whole, therefore, the sets can hardly be said to be of much benefit where pressure has to be resisted. Despite this, the system has been of immense service in mining wide lodes, but for all that, it can only be pronounced a makeshift.This is no reflection on Deidesheimer, the famous originator of the square set, for, as will be shown later on, this way of...

Jan 1, 1912

By D Mnller, J L. Mauk

The Oblaga Cu-Au skarn deposit and porphyry prospect is located in the south-eastern edge of the Gobi Desert in western Inner Mongolia. The deposit occurs within metamorphosed middle Paleozoic volcanic, plutonic and sedimentary rocks.   Ivanhoe geologists recognise eight main rock types in the area. Calcareous sediments include conglomerate, interlayered siltstone-sandstone, and limestone. Covering the calcareous sediments is a slab of thrusted biotite granite, and above it is rhyodacitic lithic tuff which, in places, is overlain by alluvial sediments. Various plutonic rocks and related intrusion breccias have intruded these units. Monzodiorite, quartz-monzonite and monzonite tend to form thin, high-angle intrusions and the youngest andesitic intrusions are generally wider and subhorizontal.   The Oblaga Cu-Au skarn, which occurs in the calcareous sediments, shows typical prograde and retrograde mineralogy. Petrographic studies show that prograde skarn minerals have been overprinted by retrograde skarn minerals, and original host rock minerals have been texturally obliterated and completely replaced. The mineralogy of the Oblaga skarn deposit is very similar to other Cu-Au skarn deposits worldwide.   Sericitic and minor chloritic alteration occurs throughout the study area and may relate to porphyry-style mineralisation. Generally, this alteration is not intense and most rocks have retained their original texture. Geochemical analyses suggest that K-metasomatism is not widespread at Oblaga. XRD analyses suggest an upward and outward transition from sericitic to chloritic alteration.   Comparisons between Oblaga and other porphyry Cu-Au deposits worldwide show that Oblaga has very similar characteristics to deposits that have undergone sericitic alteration. However, Oblaga is special because it also has relatively intense chloritic alteration, which is uncommon in other porphyry Cu deposits described in the literature.

Jan 1, 2005

By P Mulvey

"Currently mine process studies and geochemical waste characterisation are considered as two interdependent studies, necessary for the development of the mine and inclusion in the environmental impact statement (EIS). Geochemical waste characterisation will utilise the simulated tailings produced by the mine process studies team to understand the behaviour of the tailings, but the two teams rarely integrate these to develop a coherent and agreed final design.Thorough mine waste geochemical assessments can develop processes to minimise environmental harm, resulting in substantial savings in the decommissioning, closure and rehabilitation phases, and may also be able to address changes in mineral processing methods that can result in substantial savings in process inputs, or even recovery of metal concentrates.Based on geochemical waste characterisation, the full cost of waste management can be calculated and incorporated into the costing of milling.  This allows for a more effective evaluation of the metallurgy.  A number of examples are presented in which substantial improvements have been made from the collaboration of both the metallurgical and geochemical teams during planning and the metallurgical team and environmental team during operations.*This paper is only available for individual download. It is not included in the conference proceedings*CITATION:Mulvey, P, 2013. Optimising metallurgy at the planning stage to minimise environmental impact - a feedback loop from geochemical waste characterisation, presented to MetPlant 2013 Conference (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jul 15, 2013

Peculiarities of Quartz Distribution in Zinc Flotation Products and their Influence to Mineral Processing

Sep 13, 2010

By W T. Yen

Pyrrhotite crystallises as either a hexagonal or monoclinic structure, both of which can occur in ore deposits. In general, pyrrhotite is not considered as a valuable mineral unless it contains considerable amounts of other metals like nickel or copper. In fact it causes numerous problems in flotation including intensive oxygen consumption, which results in poor selectivity among sulphide minerals in the processing of complex sulphide ores. Also, because of its high sulphur content, pyrrhotite is a major contributor to environmentally detrimental sulphur dioxide (SO2) emissions from smelters. Pyrrhotite also interacts galvanically with grinding media via electrolyte species present in the flotation pulp, resulting in media corrosion. The most effective way to reject pyrrhotite is through a separation stage, which may be difficult when both types of pyrrhotite are present in the ore. In this regard depression of pyrrhotite through a flotation stage may be applied. Pyrrhotite depression by either intensive oxidation or by using sodium cyanide has been practiced. Results present in this work show that NaCN can depress pyrrhotite effectively when combined with an alkaline environment and low collector concentrations.

Jan 1, 2002

Flow Sheet Simulation of Municipal Waste Treatment Processes

Sep 13, 2010

The selection of the best comminution circuit for the preparation of concentration feed is a compromise based on economics, energy efficiency, labour costs, steel consumption, availability and other factors specific to each case. It is postulated that the selection must be a choice of one of the eight basic comminution circuits which can be divided into two basic groups, (1) autogenous or semi-autogenous primary mills with or without a secondary grinding stage and (2) fine crushing usually in cone crushers followed by a rod mill-ball mill circuit or a single stage ball mill circuit. The accuracy of selection may be improved by pilot plant and laboratory tests which are described in this paper. For (1) above, testing includes media competency tests with standard impact crushing, grindability and abrasion tests followed by pilot plant tests. For (2) above, bench scale crushability, grindability and abrasion testing is available. It is suggested that, through these tests, it should be possible to eliminate all but one in each group of basic comminution circuits. Then engineering and economic studies should lead to the best comminution circuit for the specific requirement.

Jan 1, 1984

By R J. Holmes

An accurate knowledge of the chemical, mineralogical and physical characteristics of ores and mineral products that are mined, processed and traded is crucial to effective resource utilisation, plant design, process optimisation and finally quality control to ensure that contract specifications are met. However, all too often the responsibility for sampling is entrusted to managers and personnel who do not fully appreciate the significance and importance of collecting representative samples for analysis, and everyone seems satisfied as long as some material is collected and returned to the laboratory for analysis. Furthermore, sample stations incorporated into the design of new plants are often the first casualties when cost cutting exercises commence. This needs to change, because there is little point in accurately analysing samples if they are not representative in the first place. The resultant analyses can be next to meaningless and the effort taken to analyse such samples is to a large extent a waste of time and resources.Ultimately, a poor knowledge of the characteristics of ores and mineral products limits the ability of mining companies to optimise the life of ore resources and plant performance, and failure to meet final product specifications can have disastrous consequences, including price penalties and more seriously loss of sales contracts. It is high time that sampling is given the attention it deserves as the first critical step in the quality measurement chain.CITATION:Holmes, R J, 2013. The importance of sampling in the mineral industry, in Proceedings MetPlant 2013 , pp 34-49 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 15, 2013

By Higgins RJ

Environmental investigations have been undertaken by Ok Tedi Mining Limited (OTML) since 1981 when the Ok Tedi Environmental Study was commenced. Environmental monit- oring and management programmes were implemented in 1983. The programmes included water quality monitoring, river flow and sediment monitoring, surveillance of aquatic biological communities and a health and nutrition survey of the local people. These original programmes have continued, and additional programmes of work have been developed and revised to reflect changing operations and the need to focus investigations on specific areas and issues of concern. In April 1990, following the establishment by the Government of Papua New Guinea (PNG) of environmental management criteria for the Fly River system, compliance monitoring programs were introduced. Details of the compliance and additional monitoring programmes undertaken by OTML throughout the Ok Tedi and Fly catchments, including programmes of investigation in the Fly River estuary, Gulf of Papua and Torres Strait, are presented.

Jan 1, 1991

By Christie GB, Mainwaring DE, Leong YK

High solids brown coal slurries have been prepared with concentrations approaching those achieved with bituminous black coals. The high inherent water content and macroporosity of Victorian brown coals have been reduced in a controlled manner by chemical and mechanical means. The hydrophobicity of the coal surface has been increased sufficiently to reduce the tendency for swelling and water uptake. This together with densification has allowed the solids content to be progressively improved from 25% solids with raw coal to 65% solids with modified coals. Both raw brown coal and modified brown coal suspensions show shear thinning behaviour resulting in lower viscosities at higher flow rates. All coal suspensions displayed a yield stress once sufficient solids concentration was achieved. This yield stress can be used in the prevention of solids settling. Under simple shear mixing the network structure that provides the yield stress quickly breaks down to a low viscosity fluid with reduced yield stress and a pumpable consistency. The time necessary for structural recovery is in the order of days permitting shut-down and start-up of fuel delivery systems.

Jan 1, 1987

THE flotation plant at Mount Lyell was erected, primarily, for the treatment of ore from the Lyell Comstock mine. These workings are situated over a mile in a direct line north of the North Mount Lyell mine, and are connected with the Reduction Work at Queenstown by a 2-ft. gauge steel tramway via the Queen River valley a distance of 7 miles. The property was purchased from the Mount Lyell Comstock Copper Co. After the disastrous fire in the North Mount Lyell mine in October, 1912, steps were immediately taken to make Lyell Comstock ore available for treatment, in order to relieve distress caused by any prolonged stoppage of work, and subsequently 13,032 tons of ore, averaging 3.38 %copper, 0.28 oz. silver, and 0.034 oz. gold; were smelted. When operations were resumed at the North Mount Lyell mine, it was evident that there was no economic advantage in smelting Lyell Comstock ore as compared with the higher value North Mount Lyell ore, which was also a better flux for the Mount Lyell pyrites, and that the future of the Lyell Comstock ore depended upon cheap mining and successful concentration of the ore. Therefore, extensive trenching and diamond-drilling was carried out, and a sufficiently large quantity of ore proved available for cheap extraction by open-cut methods. At the same time bulk tests by flotation were carried out at the Minerals Separation testing plant in Melbourne on different classes of ore from the Mount Lyell Comstock mine proper, followed by laboratory tests at Queenstown on all classes of ore available. All these tests demonstrated that the ore was amenable to the process, provided that it was ground finely enough. Plant erection was delayed by the general dislocation of business at the outbreak of war, but finally it became...

Jan 1, 1920

MR. W. E. WAINWRIGHT occupied the chair, and in introducing the lecturer said, on account of the absence of the vice-president, it fell to his lot to introduce the lecturer. Mr. Tennberg, he said, was visiting Australia, and those present might wonder who he was.He understood that the lecturer w~s a reputable practising geophysicist, associated with a reputable company! It was rather desirable perhaps to say that the Institute had made some inquiries with regard to his status. Geophysics was a comparatively newscience, and had suffered several hard knocks in Australia and elsewhere. Most of those knocks had been the result of undue optimism of a number of people who did not understand what they were talking about. It had been claimed that geophysics was a...

Jan 1, 1930

Recent work on decoppering lead is reviewed CUS is formed rapidly even from dilute solutions of copper in lead. The mechanism of decoppering is discussed and an explanation for the retention of metals such as silver in lead is advanced. As decoppering tin appears to be an analogous process, the, Cu-Sn-S system is studied at 300°C.. CuS, which is not an equilibrium product, is found m decoppermg drosses. In the removal of nickel from lead, Ni3Pb2S2 is formed; preliminary measurements show the equilibrium nickel content to be greater than that obtained by stirring in sulphur. Decoppering bIsmuth IS thermodynamically favoured, but is complicated by the occurrence of CuBiS2 The Cu-Pb-S system IS the only one of the four studied where the equilibrium can be calculated simply, as the presence of ternary sulphIde or other phases invalidates calculations based on binary data.

Jan 1, 1971

By Wilson G. L, Lord J. H

A detailed analysis of faulting indicatcs that blocks of "greenstone" have been thrust beneath the southern end of the Mt. Isa orebodies.This "greenstone" basement is considered to be a major structural control in the localization of these orebodies.INTRODUCTIONThis paper is based on exploration carried out by Mining Corporation (Aust.) N.L. from 1956 to 1960 in the area immediately south of Mt. Isa, Queensland. During this period over 20,000 ft of diamond drilling was completed together with costeaning and geochemical exploration.Early in 1959, it became apparent that diamond drill information could not be correlated with the current geological concepts of this area and a detailed geological appraisal became necessary. In all, sixty square miles were mapped at a scale of 1 in. to 500 ft, using enlarged aerial photographs. All drill core was logged and sections re-interpreted.Professor K. C. Dunham of the University of Durham consulted on this project and contributed through valuable discussion. Dr. A. Day of the University of Sydney carried out a gravity survey in February 1960 and Dr. H. Wilshire of the same University undertook microscopic examination of rocks from the area. Certain sections of the area were investigated geochemically by Mr. K. K. Hughes of New Consolidated Gold Fields (Asia) Pty. Limited in 1960.In outlining a theory of ore genesis in the area the writers have drawn heavily on the invaluable data published by many previous workers on the Mt. Isa field, in particular...

Jan 1, 1963

By Walker G. S

A study of the crystalline materials on or near the surface of freshly made or "green" superphosphate granules and mature, "set" superphosphate granules was undertaken using X-ray diffraction, X-ray mapping, scanning electron microscopy and electron probe micro analysis techniques. Calcium sulphate (CaSO4), calcium sulphate hemihydrate (CaSO4 1/2H20), and mono calcium phosphate monohydrate (Ca(H2PO4)2H2O), were the only crystalline species present in the "green" superphosphate.In the set superphosphate however, additional compounds were present, namely complex iron and aluminium phosphates Ca(Fe,AI) H(HPO4hF2)2H2O, (Fe)3(H3O)H8 (PO4)6H2O and calcium sulphate dihydrate (CaSO4.2H2O).The complex phosphates tied up the major part of the Fe and Al in the system and were concentrated on or near the surface of the granule. An intimate mixture of CaSO4.2H2O, and CaSO4, along with the above mentioned complex Fe-AI compounds, crystallize close to the surface of the granule and cause the setting of superphosphate that takes place during storage.

Jan 1, 1980

By I M. Platten, C J. S Sangster, Y Xie

The Cononish gold-silver deposit is a steep, relatively narrow quartz-vein system, with a current total mineral resource of 154 000 oz Au and 589 000 oz Ag. The northeast-southwest trending system was emplaced into late Proterozoic metasediments, and postdates metamorphism and associated Caledonian Orogenic foliations. Assay and mineralogical data show that gold and silver is spatially associated with sulfides in quartz. The main sulfide is pyrite, but galena, chalcopyrite and sphalerite occur in small amounts. Gold occurs as electrum, with minor native gold, and silver occurs additionally as tellurides and native metal. The gold/electrum is fine-grained, generally less than 100 microns in size. The main ore shoots plunge 45¦ south-west, have a 40 m to 80 m intersection with the existing underground development and extend between 40 m and 260 m down plunge. Small-scale sulfide-bearing domains within the vein carry the highest gold grades. They collectively define the ore shoots, where one or two, and rarely three, of the domains are present at an individual site in the vein. Discontinuity of individual domains, variation in domain thickness and internal heterogeneity results in short scale variation in grade across the structure. Geological mapping along a 1.2 km exploration adit has provided critical æconditioningÆ data to support resource evaluation based on development and relatively wide spaced drilling. In addition, it has provided an indication of potential challenges that could be encountered during production.

Jan 1, 2009

By Turnbull A. G

Thermodynamic calculations based on the ideal system NiO - Fe203 - H2(g) - CO(g) - H2O(g) - CO2(g) show that it is not possible to selectively reduce nickel oxide in the presence of hematite because ferronickel is the zero-valent nickel-containing product. The calculations show that temperature, reducing atmosphere composition and oxide to reductant ratio have a marked effect on the nickel content of the ferronickel alloy and the amount of nickel reporting jn the alloy. The general trends based on the calculations correlltte well with experimental observations.

Jan 1, 1980

A survey has been undertaken of the petrography of North Island greywackes with a particular focus on the occurrence in them of smectite (swelling clay) and chlorite, two minerals that are closely associated, chemically similar, and commonly interlayered with each other. Smectite is the mineral which is a major cause of greywacke aggregatesÆ poor performance. Smectite occurs in post-metamorphic shear zones and in surface weathering profiles over greywackes. This study focuses on the petrography of fresh greywacke rocks.   The occurrence and abundance of smectite and chlorite and their relationship in greywackes is largely a function of the chemistry of the sediment and the maximum temperature that the sediment has been subjected to during diagenesis and/or very low grade (anchizone) metamorphism. Rock chemistry, particularly total iron and MgO, determines the smectite and/or chlorite content in fine-grained greywackes (argillites and siltstones) but chemistry is less influential in sandstones, where at low grades of metamorphism much of the Fe and Mg of the rock is held in unreacted detrital minerals and the mineral constituents of lithic grains.   Four zones which represent different levels of diagenesis and very low grade metamorphism, based on the crystallinity of illite and chlorite in the greywackes, and the proportion of smectite interlayered with chlorite, have been mapped in the North Island. In the anchizone smectite does not appear as a discrete mineral, it is always interlayered with chlorite. In the upper anchizone chlorite contains approximately ten per cent of smectite interlayered with chlorite. In the lower anchizone about 30 per cent smectite can occur in chlorite.   In addition to the smectite and chlorite inherent in the greywackes as the result of the thermal overprint, smectite as a discrete mineral and smectite-chlorite interlayered minerals with high levels of smectite, occur in abundance on shear zone surfaces and in alteration zones adjacent to shear zones; these are the main contributers to the high levels of smectite recorded in many greywacke aggregates.

Jan 1, 2006

By M Stewart

Alluvial gold deposits in the area studied are preserved on the valley floor and elevated terraces due to a sequence of glacial/interglacial events during Pleistocene and Recent times. Continued regional uplift has overprinted these events. Prospecting by drilling and bulk sampling has demonstrated a complex alluvial gold resource which is now being mined.

Jan 1, 1989