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The paper examines the value of very small-scale indigenous gold mining operations to developing countries. The paper looks particularly at this type of activity in two neighbouring countries, Papua New Guinea and the Philippines, considering technical, economic, social and environmental aspects.

Jan 1, 1990

The Hill 50 Gold Mine is situated at Boogardie, 3 miles on a bearing of 295 degrees from; Mount Magnet township. Mount Magnet lies 300 miles north-north-east of Perth, Western Australia (Fig. 1).The older workings of the mine may be identified with those of Sirdar, Gold Mining Lease 696M The Sirdar had been worked before 1902 though no records remain, and irom 1903 to 1912 about a thousana tons at a grade of 6' 2 dwt. was extracted annually; by the end of 1918 6,225 oz. of gold had been obtained from the milling of 17,852 tons of ore. In view of these yields, and the length and width of the lode, this mine was early recognized as one of the most promising in the district. From 1919 to 1924 the ground,including G.M.L. 1282M, was held as Mt. Zion G.M.L. 1183M.The Hill 50 Gold Mine N.L. company took up the workings as Hill 50 G.M.L. 1282M in 1934 and have continued operations to the date of writing. To the end of 1956 the Hill 50 Gold Mine had yielded 982,106 tons of ore for a return of 448,'602 fine oz. of gold.The mine has been described by: J utson (1915), Feldtmann (1920), Johnson (1949), and Finucane (1953). Finucane (1953) details the mine structure to a depth of 414 ft. The author was able to examine the mine to a depth of 1305 ft. Detailed main level mapping to the 1060 level and a detailed surface examination have revealed aspects of the structure which were previously obscure.

Jan 1, 1960

Following a decline in direct and indirect employment in the minerals industry between 2000 and 2003, the situation reversed in 2004 and employment rose by 12 per cent. Furthermore, there are forecasts of continuing employment growth in the minerals industry in the immediate future. For those of us charged with promoting the virtues of a career in the minerals industry this is encouraging news, as it provides us with the evidence to promote the increasing employment opportunities of a healthy and vibrant industry. However, for many others û particularly the employers in this industry û the news is not so rosy. The jobs are there, and in increasing numbers, but the workers arenÆt! Employers right across the industry are finding it increasingly difficult to fill vacancies with suitably qualified and skilled employees and the competition is becoming fiercer. In the minerals and energy sector, questions are being asked and solutions sought on the industryÆs ability to attract and retain a skilled workforce. From many quarters û industry, government and the education sector, calls for urgent action are becoming louder. The reasons for this are well known û the nature of the work, the remote location, perceptions of the industry, an aging workforce, the gender imbalance, the shrinking demographic of school leavers. It is the latter I wish to focus on û the Generation Y demographic û those who have recently left school, those who are in higher education or have recently entered the workforce, or those who are still at secondary school. These young people are the next cohort of potential employees for the industry. But our need for them appears to be greater that their perceived need for us! How do we engage them so they are informed about the industry? How do we inform and advise them so they are prepared to consider further education and training in disciplines and skill areas relating to our industry? How do we guide and motivate them to give it their best shot and work in it û at least for part of their working life? These are fundamental questions that many within the industry have been grappling with for quite some time. Let me share with you some of the strategies that the Minerals Council is implementing to address this issue.

Jan 1, 2005

By D Gelling

Mineral sands dry plants consist of a large number of repetitive unit operations with significant transport delays, in the form of stream pipes, conveyors and elevators. As part of the P255 mineral sands sponsorship and using the JKMRC developed conductor/non-conductor (CNC) gauges, control loops have been implemented at the multi-duty dry plant of Cable Sands Limited at Bunbury. This paper describes the loops for kV control on a rougher high tension roll machines (HTR). The options available are product grade control and ratio control using the JKMRC CNC gauges, which measure the percent conductors in a stream. The purpose of control is to stabilise the circuit operation against disturbances such as atmospheric and feed disturbances.

Jan 1, 2001

By J Fisher, M Castro, A Hariyadi

The train haulage system being designed for PT Freeport Indonesia’s Grasberg Block Cave (GBC) will be located within the mine at an elevation of almost 3000 m above sea level on the west side of the island of Papua, Indonesia. The developing block cave is beneath the active Grasberg Open Pit and will transport 160 000 t of ore per day from multiple chute galleries to the underground crushing plants. The design entails 28 km of rail and 119 ore chutes, which will be brought online over the course of ten years.The train haulage system will be driverless and fully automated. Sequentially, the system includes remote controlled rock breakers at the top of the chute grizzlies, followed by remote controlled chute loading of the trains, then autonomous train haulage and autonomous unloading. An overhead catenary system (OCS) will power the locomotives, which are equipped with on-board batteries to drive through the loading and unloading sections. Service locomotives with drivers move material-laden freight cars in and out of the service shaft, destined for workshops, the magazine and batch plants. Service locomotives are also used for haulage level maintenance. Highly reliable and redundant control and communications systems are required to manage 12 trains in simultaneous operation.This paper provides an overview of the train haulage system’s technical complexities and the associated support systems interactions. The paper also highlights the project management issues and successes of this globally sourced project.CITATION:Hariyadi, A, Castro, M and Fisher, J, 2016. Automated train ore transport, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 563–570 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By D Pilone

The Tyrrhenian micro-nodules, findable at low depths (200/600 m under s l) are a reasonable reserve of manganese. They can be easily and cheaply recovered but do not contain valuable metals as in the case of oceanic nodules. In this work a hydrometallurgical process for manganese recovery from Tyrrhenian nodules is presented. The studied treatment includes the following operations: magnetic enrichment, reducing leaching, leach liquor purification and electrowinning . The study shows that the most important step in the process is the preliminary manganese enrichment. It can be done directly on the platform reducing not only the transport cost, but also the residue mud in the metallurgical plant. The leaching parameters such as status and size of nodules, temperature, composition of leaching solution and S/L ratio have been investigated. After purifying the leach liquor by iron precipitation as ammonium jarosite , the conditions to electrowin manganese have been investigated. The yields of both manganese leaching and iron precipitation together with current efficiency and specific energy consumption in the electrowinning step are given.

Jan 1, 2000

The oxidation of ferrous sulphate to ferric sulphate with air and oxygen in a gas lift percolator was investigated with initial Fe2+ concentrations in the range 0·01 M to 1·0 M,temperatures in the range 20-80°C, and pH in the range oto 2.The rate of formation of Fe3+ was found to be well described by the rate expressionEquation 1and a consistent mechanism is proposed.The presence of Cu2+ was found to cause an increased rate of oxidation, the effect being greater with Cu2+ concentrations increasing in the range 0·001 M - 0·01 M in 0·2 M Fe2+. The effect of other solutes containing Ni, Zn, Mn, Co, Hg, Cl, Mo, NH4, As, Cr, or Na at a concentration of 0·001 M in 0·2 M Fe2+ was negligible.

Jan 1, 1972

By B B. Beamish, J Theiler

Current spontaneous combustion index parameters such as SHT, CPT/RIT and R70 self-heating rate all have deficiencies that need clarifying from a risk management perspective. In some instances they can produce a false negative evaluation and in others they can produce a false positive evaluation. These tests all use a relative rating scheme that does not provide any indication of the time it takes for a spontaneous combustion event to develop, nor do they consider the moderating influence of moisture present in the coal on self-heating rate in the low temperature oxidation region. This is viewed as a major deficiency since the true self-heating behaviour of broken coal is primarily a function of time that is governed by the interaction of the initial boundary conditions (initial ambient temperature and moisture state) with the reactivity of the coal (both intrinsic coal reactivity and accelerated self-heating from reactive pyrite if present). The current index tests are also not appropriate for assessment of coalmine immediate roof and floor rocks.CITATION:Beamish, B B and Theiler, J, 2017. Recognising the deficiencies of current spontaneous combustion propensity index parameters, in Proceedings Australian Mine Vent Conference 2017, pp 113–118 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017

Solvent extraction has recently been introduced into Australian hydrometallurgical practice for the production of a high grade uranium concentrate from El Sherana ore by a sulphuric acid leach and solvent extraction process. The solvent is a 5 per cent solution of tri(iso-octyl)amine in kerosene modified with 4 per cent of a long chain alcohol. The stripping reagent is a molar solution of sodium chloride.Preliminary testing for the development of the process showed that the leach liquor was quite amenable to the solvent extraction process and that the equilibrium and rate considerations of both the extraction and stripping steps were very favourable.The industrial plant contains four stages of extraction, three stages of chloride stripping and one stage of secondary carbonate stripping. An internal type of mixer-settler is used for the stagewise contact, the design being based on tests with model equipment.The performance and control of the industrial plant is satisfactory; 99·7 per cent of the uranium is recovered for a loss of 0·3 gallons of kerosene and 0· 4 pounds of amine per 1,000 gallons of liquor treated.INTRODUCTIONThe processing of El Sherana uranium ore from the South Alligator River valley commenced in April, 1959, and thereby introduced into Australian hydrometallurgical practice the unit operation of solvent extraction on an industrial scale. Although there are now some twelve mineral processing plants in the United States and Canada using solvent extraction, its application to the field of primary hydrometallurgy is quite new. Prior to 1956 none of these twelve plants was operating and hydrometallurgical application waslimited to the refining of comparatively high grade uranium compounds and fission products from nitrate and nitric acid solutions.

Jan 1, 1961

By G A. Ekama

This paper describes a novel system for the biological sulfate reduction (BSR) of acid mine drainage (AMD) using primary sewage sludge (PSS) as carbon source in an upflow anaerobic sludge bed (UASB) reactor configuration. A UASB reactor was operated at a temperature of 35¦C and it received PSS (1875 mg/L COD) augmented with sulfate (1500 mg/L SO42-). The experimental results indicate that a high treatment efficiency was achieved at more than 90 per cent sulfate reduction at a liquid hydraulic retention time (HRT) of 13.5 h. In this study, the effects of various operational parameters were also investigated. The effect of a biomass recycle stream from the top to the bottom of the sludge bed was found to initiate rapid BSR from the bottom of the bed. Profile tests showed that effective and immediate sulfate reduction was achieved as soon as the influent entered the reactor. From these results, it can be concluded that the UASB configuration using PSS as energy source would be a viable method for the BSR of AMD.

Jan 1, 2009

By J R. Manuel, J M. F Clout

The importance of goethite to Australian iron ore production is steadily increasing as the proportion of goethite-rich, martite-goethite bedded and channel iron deposits increases at the expense of declining production from high-grade microplaty hematite deposits. For this reason, an improved understanding of goethite in iron deposits, its genesis, goethite types and their physical and metallurgical properties is vital to maintaining optimum sintering and blast furnace performance in Asian steel mills.The terminology used to describe goethite in Australian iron deposits is currently highly variable. The discredited mineral name ‘limonite’ is still in widespread use as a field term for goethite and there are many misconceptions concerning goethite chemical grade and downstream physical and metallurgical properties. The goethite classification proposed here is based on geological and physical properties from which three types are recognised including brown goethite, dark brown-black vitreous goethite and highly microporous, friable yellow ochreous goethite.In practice, typical vitreous goethite with highly reflective surfaces and conchoidal fracturing, characteristic of the hard cap zone appears from X-ray fluorescence (XRF) and electron microprobe analysis to be significantly higher in Si (up to 18.7 wt per cent), Al (up to 3.5 wt per cent) and S (up to 0.14 wt per cent) compared to the generally very low (<1 wt per cent for Si and Al) levels of these elements in ochreous goethite and brown goethite. The data dispels the common misconception that friable earthy or yellow ochreous goethite is high in Al and Si and other chemical impurities. However, P was found to be consistently higher (mean of 0.112 wt per cent and up to 0.296 wt per cent) in ochreous goethite than brown goethite (mean of 0.011 wt per cent) or vitreous goethite (mean of 0.031 wt per cent). The highly porous microstructure of ochreous goethite is thought to have a much higher surface area, which may aid in preferential adsorption of P onto the ochreous goethite mineral surface.CITATION:Manuel, J R and Clout, J M F, 2017. Goethite classification, distribution and properties with reference to Australian iron deposits, in Proceedings Iron Ore 2017, pp 567–574 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

For small particles of niekel flotation eoncentrate (av. size 50 pm) the predominant heat transfer mechanism under suspension smelting conditions, prior to ignition, is conduction from the gas and not radiation from nearby hot bodies. Results of laboratory tests using gas temperatures 380-700°C and furnace wall temperatures 380-1100°C were in accord with heat transfer theory. In practieal flash smelters earlier ignition, and hence better utilization of the space in the shaft, would result from introduetion at the top of the shaft of gases hotter than the ignition temperature of 500-600°C.

Jan 1, 1979

Updraft sintering of lead concentrates was introduced at Port Pirie in 1955 and since that time a considerable amount of investigational work has been carried out in the laboratory and on the plant with the objective of improving both the understanding of the process and its practical application.From this work it is now possible to predict trends in design and operation, which should result in capital savings and increased efficiency of future updraught plants.INTRODUCTIONOver the last 70 years a remarkable advance has been made in the method of preparing lead concentrates for smelting in the Port Pide blast furnaces of The Broken Hill Associated Smelters Pty. Ltd. (RH.A.S.). Beginning in 1889 with heap roasting, the process progressed to Ropp roasters and Huntington-Heberlein pots in various combinations, then to multiple small Dwight Lloyd (D.L.) downdraught machines. In 1940 two large 10 ft by 50 ft D.L. downdraught machines were installed, and finally in 1955 updraught sintering was ,introduced with the installation of the present 10 ft by 99 ft sinter machine.At the time this last machine was built it was the first unit of its type and thus, of necessity, an experimental machine. During the eight years it has been operating a considerable amount of investigational work on sintering has been carried out both on the plant and in the laboratory.It is now felt that sufficient information is on hand to predict at least tentatively, some of the future developments in lead sintering, whereby both the quality of the sinter and the rate of production may be improved. This will result in a considerable reduction in smelting costs.

Jan 1, 1964

This paper reviews the manpower requirements of the Australian mining industry. It has been necessary to provide general background information in order to support the view that university education in mining and mineral process engineering should be strengthened rapidly in Australia to provide graduates for the industry.

Jan 1, 1969

By B M. Wilson, B J. Turner, S Sinclair, R J. Buerger

The Trident Gold Deposit is centred on the historical Higginsville Mining Centre, between the world class gold centres of St Ives (+15 Moz) and Norseman (+6.5 Moz) in Western AustraliaÆs productive eastern goldfields. It lies towards the southern end of the Norseman-Wiluna Greenstone belt in the Archaean Yilgarn Craton. The current in situ resource for Trident is estimated at 840 000 ounces, with production to date in excess of 500 000 ounces.Trident is hosted primarily within a thick, weakly differentiated gabbro with subordinate mafic and ultramafic lithologies and comprises a series of north-northeast trending, shallowly north plunging ore zones. The deposit comprises two main mineralisation styles; thin, lode-style, nuggety laminated quartz veins (Athena and Artemis) that formed along major shear zones primarily at the contacts between the various mafic and ultramafic lithologies; and large wallrock-hosted ore-zones comprising sigmoidal quartz tensional vein arrays and associated metasomatic wall rock alteration (eastern zone, western zone and Apollo) hosted exclusively within the gabbro.The thin laminated quartz vein lodes are important to the Trident Gold Deposits production profile as they constitute 33 per cent of the metal from only 14 per cent of the tonnes. The delineation, grade estimation and extraction of these lodes require a disproportionate amount of geological and engineering input due to the small scale variability in width, grade and direction. Over time, a robust and thorough process has been developed at the Trident Gold Deposit to understand and then successfully mine these complex mineralised systems.CITATION:Sinclair, S, Wilson, B M, Buerger, R J and Turner, B J, 2012. The mining industry needs to be shaken and stirred, in Proceedings Narrow Vein Mining 2012 , pp 155-166 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 26, 2012

THE most important part of the routine survey work on a mine is the keeping up-to-date of plans and sections showing progress of stoping and development work, and the direction of the latter for the purpose of making necessary connections. Except in specialcircumstances, e.g., major horizoittal development, the exactitude required in this work is not extreme, and a method of survey in keeping with the demands of the work itself is all tbat is required.For example, no one would consider measuring the walls of a stope to a fraction of an inch; such extreme accuracy would be wasted.The stope walls being irregular, a mean is usually taken, and for ordinary purposes a survey with a limiting error of six inches is quite satisfactory for the purpose of plotting either stoping or development.It is the author's aim in this paper to describe the method in use at the North Broken Hill Oompany's British mine. This method, while being sufficiently accurate for the purpose in view, possesses the very great advantages of speed and simplicity of operation,with a minimum of necessary equipment. This latter is a very important item where several surveys on different levels have to be carried out on the one day.Let it be understood, however, that the use of this method does not dispense with the theodolite, but simply serves as a convenient adjunct to obtain details and to extend the accurate theodolite survey up rises and down winzes, and through ladderways orwinzes into stopes, where the use of a theodolite, if not actually impossible, is often exceedingly inconvenient. This is particularly so on the British mine, where a large proportion of the ore is won from narrow and complex-dipping lodes, and where vertical ore...

Jan 1, 1928

Neither the copper orebodies nor the zinc-lead-silver orebodies at Mount Isa were formed syntectonically as has been claimed for the last 20 and 10 years respectively. Both orebody types were cogenetic, coeval, and formed early during the sedimentation and diagenesis of the host formation. The copper orebodies are interpreted as having formed diagenetically at hand specimen scale, syngenetically at formation scale. The zinc-lead-silver orebodies are interpreted as having formed primarily by sedimentary means at both hand specimen and formation scales.

Jan 1, 2000

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

Laboratory and pilot plant investigations aimed at recovering gold as an electroformed sheet from gold eluate and gold leach solutions and slurries are discussed. The electrolytic test work undertaken makes use of high surface area electrodes, in particular nickel-chrome foam metal and activated carbon, as well as ultrasonic activation. The process involves initial gold electrowinning (or adsorption onto activated carbon), followed by gold electroforming, both operations being carried out in a specially designed reactor. The pilot plant work mainly involved the treatment of gold eluate solutions from a South African gold mine containing 600 mg/L Au: some tests were also carried out on gold leach solutions containing 6 mg/L Au. In the former case, very efficient gold extraction onto the foam metal cathode was achieved using electrolysis combined with ultrasonics. The polarity of the gold-loaded cathode was then reversed and, using a replacement electroforming electrolyte, gold was electroformed in situ onto a polished stainless steel mandrel, from which gold sheet was subsequently removed. In the case of leach solutions, pilot plant tests confirmed laboratory findings that in the presence of calcium (resulting from the lime used during the leaching process) no electrowinning is possible. Laboratory tests showed, however, that when sodium (in the form of NaOH or Na2CO3) is added to the leach solution, electrowinning can indeed take place. Alternatively, if a special activated carbon electrode is used (without current), the non-ionic calcium aurocyanide complex is adsorbed on to the activated carbon. When a gold-loaded activated carbon electrode is made anodic in a gold electroforming electrolyte, gold electroforming is feasible, although the efficiency is very low. The possible implications of these developments for gold recovery are further examined.

Jan 1, 2007

By A-A Latscha, C Boyle

Geological modelling has historically been done using sectional interpretation of paper sections or on a computer screen. Boundaries of geological units or grade shells are interpreted by a geologist section by section and the shapes are drawn onto paper to be digitised later or they are directly digitised into a computer. This approach is referred to as explicit modelling. Such methods are time consuming if there are many section lines or boundaries to be interpreted. The number of metres drilled and resource models made is increasing each year and it will be difficult to keep up using explicit modelling methods. Alternatively, it is possible to use information carried in the drill holes, known geological relationships and point estimation methods in two or three dimensions, to create similar geology boundaries, while eliminating or at least greatly reducing the need to manually interpret and digitise detailed sectional interpretations. Such methods are referred to as implicit modelling and are available in a number of software packages. Implicit modelling approaches have been used in iron ore and found to significantly reduce the time needed for modelling while producing results that are comparable or better than standard explicit modelling approaches. A number of case studies have been undertaken of implicit modelling in iron ore deposits. Stratigraphic surfaces of bedded, folded and faulted iron ore deposits have been modelled in various deposits by Leapfrog Geo, GOCAD (with SKUA) and Vulcan Integrated Stratigraphic Modelling. Leapfrog Mining was used to model iron grade shells at particular cut-off grades. The modelled surfaces are of a high standard equivalent to those that could be produced by traditional explicit modelling but the time required by the implicit methods is far less. Implicit geological modelling is an active area of software development and improvements in software are likely.CITATION:Boyle, C and Latscha, A-A, 2013. Implicit geological modelling of iron ore deposits, in Proceedings Iron Ore 2013 , pp 57-66 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013