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By Walters GW

A countercurrent method of metal refining using crystallization and reflux is discussed. 4n account is given of the development of this technique for the separation of silver and bismuth from lead using bench-scale studies to the present small pilot-plant unit (around one tonne per day) in the "Commonwealth Scientific and Industrial Research Organization (CSIRO)" Division of Chemical Engineering.

Jan 1, 1975

By J Savage, A Crawford, M Doyle, N McNaughton, T G. Blenkinsop

Area selection criteria for gold exploration have historically highlighted the low prospectivity of high-metamorphic grade terranes relative to regions with lower metamorphic grades. The Tropicana gold project, Western Australia, is a rare example of a major greenfields gold discovery in Archean mid-amphibolite to granulite-facies gneissic rocks that have experienced widespread recrystallisation and partial melting.The project, located on the tectonically reworked eastern margin of the Yilgarn Craton, is part of the Tropicana Joint Venture, which is 70 per cent owned by AngloGold Ashanti Australia (manager) and 30 per cent by Independence Group NL. Construction of the mine commenced in the June quarter of 2011 and first gold pour from open pit mining is anticipated in the December quarter of 2013. The approved project will have a ten-year mine life and in the first three years of operation, gold production will be between 470 000 - 490 000 oz/a at a cash cost of A$590 - A$630/oz.Reserves as at 31 December 2011 total 56.4 Mt grading 2.16 g/t for 3.91 Moz of gold. The mineral resource, as of 30 December 2012, has grown to 7.89 Moz of contained gold, including Inferred Resources of 11.9 Mt at 2.83 g/t for 1.08 Moz.Economic gold mineralisation post-dates peak metamorphism and is interpreted as younger in age (ca. 2500 Ma) than other gold deposits in the Yilgarn Craton on the basis of structural and geochronological constraints. Mineralisation is genetically related to an imbricate thrust stack that records a prolonged history of reactivation during the Proterozoic era. Gold mineralisation formed from higher temperature (>350¦C) silica-undersaturated fluids that preferentially migrated though a favourable intensely potassium metasomatised zone. Permeability created during brittle fragmentation was accompanied by replacement of mafic metamorphic minerals, and synchronous partitioning of strain into pervasively biotite-sericite-pyrite-altered stylolites and shear planes that bound more competent lithons.CITATION:Doyle, M, Savage, J, Blenkinsop, T G, Crawford, A and McNaughton, N, 2013. Tropicana - unravelling the complexity of a +6 million ounce gold deposit hosted in granulite facies metamorphic rocks, in Proceedings World Gold 2013 , pp 87-94 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 26, 2013

By M A. Faizulin, N G. Stukalova

The present till now practice of averaging of ore by metal content at mining-dressing enterprises does not allow evaluating objectively really existing regularities of dressing process. The processing of large statistical data by specially designed methods has revealed the relationships of extracted mass of metals into concentrates when processing of ore at preparation plants. The analysis of the obtained relationships points to necessity of timely control by flows of ore with due account of different sorts of metal. For this problem solving it is offered to use specially designed methods on carrying out of calendar planning of a mining and shipment of ore at open casts, based on ranked arriving of flows of different sorts ores to preparation plant. The given methods includes economic-mathematical model forming and its implementing by worked out method. The formed model allows taking into account different technological and organisation limits, typical operation conditions of open cast and preparation plants. Using this methods of control of mining operations and designed on its basis the complex of software allows increasing volume of metals, extracting into concentrate, up to two per cent without any additional costs and saving of the existing technological schemes at preparation plant.

Jan 1, 2003

By T. Baker

The Eloise Cu-Au deposit is 60 km SE of Cloncurry in NW Queensland and has a current indicated reserve of 3.2 Mt @ 5.8 per cent Cu, 1.5gA Au and I9g/t Ag. It is hosted by metasediments and metabasic rocks that underwent amphibolite facies metamorphism at 550-600¦C and less than 3.5 kb. Peak metamorphism coincided with the regional D2 event which produced an S2 foliation with north-south strike and variable sub-vertical to steep east or west dip. The deposit is associated with several major shear zones parallel to the S2 foliation. The lodes form part of a large alteration system that is localised by the retrograde shear zones. Homblende-biotite-quartz with minor sulphides occur early in the alteration paragenesis which is overprinted by chlorite-muscovite-pyrrhotite-chalcopyrite ¦calcite+¦nagnetite. The later assemblage replaces the earlier Fe-K alteration as well as Fe-rich metamorphic assemblages such as homblende, biotite and staurolite indicating a post peak metamorphism timing for ore formation. Although replacive textures are the most common, the alteration can display open space infill and brecciation as well as durchbewegung and mylonite textures indicating that mineralisation occurred during ongoing ductile deformation. All these features are crosscut by a later brittle phase of calcite-chlorite-quartz¦pyrite alteration.

Jan 1, 1994

By S Munn

Today, it can be said that the majority of mines utilise communications equipment in one form or another. Either for communications between staff making their day-to-day operations more efficient, or for emergency communications, as well as linking computer based mine management systems, and providing remote control over complex mobile and fixed machinery. With the advances in technology now available, we are moving into the next generation of mine communications equipment, using digital communications in the underground mine environment. It is a proven fact that an efficient underground mine communications system can help maximise production, by providing major gains in areas such as equipment and manpower utilisation, staff and vehicle tracking, reaction times to break downs and emergencies. In this paper we will describe some of the facilities that are currently available, as well as what will soon be available to mining and tunnelling companies around the world.

Jan 1, 1999

By D Capstick, M B. Ebell

This paper describes the test work, process design, commissioning and operation of a processing system at the Ergo gold operation that improves the extraction efficiency from gold tailings material. The improvement in recovery is derived from the separation of the gold contained within the sulfides of the tailings material and a dedicated process stream to recover that gold.The sulfides are separated by means of a flotation circuit and that resulting concentrate is subjected to a regrind of below 20 ¦m to enable a greater liberation of the gold. The ultra-fine material is then subjected to a dedicated leach circuit to recover the now exposed gold particles.The case study is an example of the challenges of introducing new technology and methodologies to a well-established operation and thereby attaining improved efficiencies and tangible business benefits.CITATION:Ebell, M B and Capstick, D, 2013. Improving extraction efficiency from Witwatersrand gold tailings using flotation and ultra-fine grinding of concentrates, in Proceedings World Gold 2013 , pp 301-306 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 26, 2013

By A Bax, G Wardell-Johnson, W P. Staunton, J McGrath, J J. Eksteen

Since 2001, the AMIRA P420 gold processing technology project series has been studying the recovery of gold using gravity devices, with particular emphasis on the centrifugal units, Knelson and Falcon concentrators. The work has entailed the surveying of operating gravity circuits in Australia, Africa and North and South America.This paper reviews some of the results and lessons of these studies, including common circuit operating and design factors, which limit gravity recovery; pointers towards effective modelling of gravity circuits; and the contribution of gravity to overall gold recovery.CITATION:Wardell-Johnson, G, Bax, A, Staunton, W P, McGrath, J and Eksteen, J J, 2013. A decade of gravity gold recovery, in Proceedings World Gold 2013 , pp 225-232 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 26, 2013

The mining industry continues to faces significant challenges due to increasing resource constraints (quality of ore bodies, water, energy, human resources) and increasing license to operate requirements (safety, health, environment, location) from society, employees and shareholders. Technology advancements and hence research are necessary to ensure that the industry remains viable in this changing environment. Collaborative research is an important part of a company's research portfolio and offers the opportunity for the industry to work on generic issues that it is facing. Obvious benefits include the reduced cost to individual companies by sharing the costs, the opportunity to leverage government funding and the opportunity to conduct longer term projects resulting in skills development (PhD and MSc). Limitations of collaborative research include the reduced focus on company specific issues and the loss of competitive advantage from owning the outcomes of the research. The challenge for researchers and research managers is for them to demonstrate the value derived from longer term, pre-competitive collaborative research. The competitive advantage is not necessarily derived only from the outcomes of the research but rather from the company's ability to direct the research, translate the generic research outcomes to address company specific issues and to implement improvements at its operations. Implementation remains the greatest challenge. In this paper, case studies of selected collaborative research projects are presented to demonstrate key success factors required for implementation of research outcomes. This is an ABSTRACT ONLY. A full-length paper was not prepared for this presentation.

Sep 13, 2010

By C Zhang, I Canbulat, G Fan, D Zhang, C Wang

A clear understanding of the intensity of coal and rock burst is the basis for future research on burst mechanism and control. There has been a wide variety in the description of coal and rock burst damage at different countries using multi-methods, which makes the common understanding even more challenging. Therefore, this paper presents a broad review on the quantifications of intensity of coal and rock burst and seismic risk around the world, considering critical factors including seismic energy, magnitude, peak particle velocity and ejection velocity. It is found that the seismic energy of coal and rock burst can widely range from 0.002 MJ to 60000 MJ, with equivalent Richter magnitude from -1 to 4. The daily seismic energies can be used for seismic risk potential assessment, with energy levels from 0.1 KJ to 10 MJ, which is much lower than the burst sources. The magnitude of the seismic events can be also estimated based on the weight of damaged coal mass and human senses of vibration and sound. For the seismic intensity represented by peak particle velocity (ppv), it keeps constant within fault radius and attenuates with a speed of 1/r4 and 1/r in near and far field respectively, thus it is possible for a small seismic event to induce considerable ppv causing severe damage if the epicentral distance is small enough. There has not been a strong correlation between the ejection velocity and ppv, as seismic energy is only one of the energy sources that contribute to the kinetic energy of burst damage. CITATION:Wang, C, Zhang, C, Canbulat, I, Zhang, D and Fan, G, 2018. Intensity quantification of coal and rock burst risk – a review, in Proceedings The Fourth Australasian Ground Control in Mining Conference (AusRock), pp 223–233 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 30, 2018

By S R. Pecover

AustraliaÆs opal and sapphire mining industry has fallen from its peak in the 1980s and 1990s into a significant low today. This is not due to exhaustion of the resource, but instead an over-reliance of the Australian miner on achieving a fair price for the gemstone product from offshore middlemen dealers. Gemstone and geological research is also at a low as Federal higher education expenditure has fallen with research institutions relying increasingly on private funding in an environment of restricted autonomy and flexibility for researchers. What little remaining research skills the universities have is being bled into the private sector as a result of the mining boom and encouraged by lower than average academic salaries. Nevertheless, some highly innovative research has been taking place, often by self-funded individuals and retired academics simply with a desire to advance the understanding of the particular branch of science in which they are interested. New models for the formation of sapphire and opal are now beginning to be applied to the exploration for these gemstone commodities. This research, together with well thought out plans for managing the gemstone product through its value-adding steps to the jewellery retail level, has the potential to bring about a resurgence in the Australian gemstone industry.

Jan 1, 2008

By C I. Edwards

Phosphorous is typically present in iron ore either in the mineral apatite, Ca5(PO4)3OH, or associated with the goethitic fraction of the ore. In this paper, we present results that show that phosphorous associated with the goethitic fraction can be removed with a heating pretreatment around 300 176;C for 1 h, followed by a caustic leach with 1 - 5 M NaOH, or a leach with sulfuric acid at pH 0.5. The heating pretreatment is considered to dehydroxylate the goethite to form a haematite intermediate phase, ‘protohaematite’, that reacts during the leach making the phosphorous accessible to the leachant. In the acid leach, ten to 15 per cent of the sample was dissolved to obtain a leach product with 0.08 per cent P. In the caustic leach, as no weight loss occurs, it is proposed that iron species associated with the protohaematite have either not dissolved or have reprecipitated at the high pH values of the leach.For an ore containing apatite as the source of phosphorous, a leach with sulfuric acid dissolved the apatite, lowering the phosphorous levels in the sample. The sample treated contained carbonate minerals (including siderite) that also reacted with the acid, and in practice a balance between the dissolution of the apatite and the carbonate minerals may be needed to minimise acid consumption.

Jul 11, 2011

By A P. Wibowo

Indonesia holds a significant role in the utilisation of coal resources in the world. Although the number of Indonesian coal resources and reserves do not fall into the world’s top ten, according to 2009 statistics, Indonesia is the seventh largest producer of coal with a production of 256 Mt. More than 80 per cent of this amount is sold in the export market, making Indonesia the world’s second largest coal exporter. Most of the exported coal from Indonesia is used to fulfil the needs of the Pacific market, such as Japan, Taiwan, China, among others. It is also possible to reach the Atlantic market.Along with Indonesia’s development program, until 2025 the Indonesian government has adopted a National Energy Policy that aims to reduce the role of petroleum in electricity generation and replacing it with coal. As a follow-up of the policy, since 2009 PT PLN, the state electricity company has built steam power plants throughout Indonesia as an implementation of the first stage of the Electrical Acceleration Project with a capacity of 10 000 MW. Moving forward, in 2011 PT PLN will also build the second stage of the project with a capacity of 10 000 MW. As a result of the program, the domestic need for coal is expected to increase as much as 44.8 Mt.With the increase in domestic need and decrease in the number of reserves, the Indonesian government has adopted policies to secure the domestic coal supply. A policy that may potentially be adopted by the government is the limiting of coal production, seeing the high rate of increase in Indonesian coal production. The adoption of such a policy will change the distribution map of coal in the Pacific market. Thus, this paper will evaluate the change of coal distribution patterns in the Pacific market along with the increase in Indonesian domestic needs and Indonesian adoption of policies regarding the securing of coal supplies.

Nov 22, 2011

By G DeschOnes, M Fulton

The Eleonore property (James Bay district of Northern QuTbec), owned by Goldcorp, hosts gold within stockworks of quartz-tourmaline-arsenopyrite veins and veinlets contained within microcline (potassic alteration) and brown tourmaline replacement zones. The preliminary investigation to recover gold from drill core samples showed that flotation followed by ultra-fine grinding and cyanidation is the preferred option. Ultra-fine grinding is used to liberate gold finely disseminated in sulfides. The flotation concentrate used in the investigation had a P80 of 11 ¦ and contained 75.5 g/t Au, 5.0 g/t Ag, 10.3 per cent S, 0.07 per cent Cu and traces of antimony (0.03 per cent). The mineralogical characterisation showed the presence of 65 per cent gangue minerals, 23 per cent pyrrhotite (hexagonal), 9.6 per cent arsenopyrite, 2.2 per cent pyrite and 0.08 per cent chalcopyrite with trace amounts of galena (0.05 per cent) and sphalerite (0.03 per cent). Gold was in the form of native gold and electrum. A straight cyanidation conducted at pH 11.0, DO of 3 - 5 ppm, 2000 ppm NaCN, 20¦C and for 72 hours extracted 97.0 per cent Au and consumed 31.5 kg/t NaCN. The equilibrium was reached within 24 hours. Increasing the dissolved oxygen to 16 ppm reduced the consumption of cyanide to 22.0 kg/t with 96.7 per cent Au extraction. A 16-hour pretreatment with 2.0 kg/t lead nitrate, followed by a 24-hour cyanidation reduced the cyanide consumption to 6.0 kg/t with a gold extraction of 97.5 per cent. Increasing the lead nitrate addition to 6.0 kg/t reduced the cyanide consumption to 1.2 kg/t by passivating the surface of pyrrhotite. The gold extraction remained at 97.0 per cent. It was possible to decrease the concentration of cyanide to 800 ppm NaCN without compromising gold extraction. The associated cyanide consumption was 1.2 kg/t NaCN. The passivation of gold grains was an issue when the cyanide concentration was decreased to 550 ppm NaCN. The gold extraction decreased to 92.2 per cent. The average lime addition for all the tests was 7.4 kg/t and the average silver extraction was 80 per cent. Efficient cyanidation of an ultra-fine sulfide concentrate with only 800 ppm NaCN represents an advance in leaching of ultra-fine sulfide concentrates. The high addition of lead nitrate would certainly make cyanide destruction easier; consequently reducing the effluent treatment costs and making possible to meet the discharge regulations criteria.CITATION:DeschOnes, G and Fulton, M, 2013. Design of a leaching strategy to extract gold from Eleonore Mine ultra-fine sulfide concentrate, in Proceedings World Gold 2013 , pp 71-78 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 26, 2013

By F Cesnik

The past few years has seen a concerted effort to improve the recovery of gold along with its co-product copper from the æhigh-gradeÆ Ridgeway concentrator at Newcrest Mining LtdÆs Cadia Valley Operations. A number of initiatives were identified and implemented, culminating in a sustained improvement in recovery of approximately three to four per cent for both metals. The key projects that contributed to this improvement included the installation of a 355 kW Metso stirred media detritor (SMD) to create a regrind circuit, installation of froth crowders on the scavenger circuit, installation of a Falcon SB2500SE gravity concentrator as part of the regrind circuit to improve gold recovered to bullion on-site and the optimisation of the grinding circuit to reduce the 80 per cent passing size (P80) of the primary grind from 160 to 121 ¦m for the same throughput via process control, cyclone and ball charge optimisation. This paper will focus on the supporting test work, where applicable, that was used as the design basis for the project, but more importantly the plant data before and after the changes to clearly identify the improvements to plant recovery.

Jan 1, 2007

By A Dal-Corobbo, R Zick

The coal mining industry is now faced with new regulatory requirements that limit the discharge of chlorides into receiving streams. To meet these new regulatory standards for treated mine water, a zero liquid waste approach was developed using advanced treatment technologies. The approach described in this paper will generate clean water for reuse in various energy endeavours or discharge to the environment, with no substantial liquid or solid waste from the treatment process leaving the site.CITATION:Dal-Corobbo, A and Zick, R, 2013. Zero liquid discharge in coal mining operations, in Proceedings Water in Mining 2013 , pp 221-226 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 26, 2013

By N J. Beukes, S T. Netshio, M O. de Kock

The Thabazimbi iron ore deposit comprises a series of stratabound orebodies, on average 18 - 25 m thick that are aligned along the faulted basal contact between the Penge Iron Formation and dolostones of the Malmani Subgroup, Transvaal Supergroup. Field geological relationships and petrographic observations suggest that the formation of high-grade iron ores took place after contact metamorphism related to the intrusion of the Bushveld Complex (2.06 Ga) but before the deposition of red beds of the Waterberg Group at ca 1.9 Ga. Hard, high-grade iron ores are predominantly composed of martite and microplaty hematite. Goethite is restricted to supergene-modified ores close to the Late Cretaceous û Early Cenozoic Old African land surface. At depth, the high-grade hematite ores interfinger with low-grade dolomite-hematite and calcite-hematite ores. Iron oxides (martite, microplaty hematite) present in these low-grade ores are texturally indistinguishable from those in the associated high-grade ores, ie ore formation is genetically associated with carbonate metasomatism. Microthermometric studies of fluid inclusions in sparitic carbonates and rare megaquartz reveal their hydrothermal origin. Two compositionally distinct aqueous fluids of shallow crustal origin are identified, namely a Ca-Na-rich high-salinity brine (26 wt per cent NaClequivalent, TH ~160¦C), and an aqueous Mg-K-bearing fluid of intermediate salinity (8.3 - 12.6 wt per cent NaClequivalent, TH~120 - 150¦C). The results confirm that high-grade hematite orebodies at the Thabazimbi deposit owe their origin to an event of extensive oxidative carbonate metasomatism (calcification), similar to that recognised at other important high-grade iron ore deposits in the world. Hydrothermal ore formation is both structurally and lithologically controlled. Size and quality of the orebodies was improved by Late Mesozoic-Cenozoic deep lateritic weathering as carbonate-hematite ores were enriched to friable high-grade ores, but this supergene modification is second in importance compared to the primary event of hydrothermal ore formation.

Jan 1, 2005

By Sparrow GJ, Woodcock JT

A sample of pyrrhotite flotation concentrate pulp assaying 15.3 g/t An, which had been prepared from an old tailing dump, was treated to extract the gold. Examination of the concentrate with an SEM showed that exposed or free native gold, 5-40 ¦m in diameter, was present but no locked gold was observed. Direct cyanidation of the concentrate to extract the gold showed that the flotation reagents present inhibited gold extraction. A range of pre-treatments was used to overcome these effects.Direct cyanidation for 48 h extracted only 26% of the gold, indicating possible contamination of the gold in the concentrate with flotation reagents. Pre-treatment of the concentrate pulp by aeration for 24 h, or by 72 h aeration with an addition of 3.65 kg/t of sodium sulphite, gave little improvement in gold extraction by subsequent cyanidation. Pre-treatment by filtration, or by aeration with 12.5 L/t 100 volume hydrogen peroxide, followed by cyanidation for 48 h gave gold extractions in the range 67-77%. Combining filtration and an aeration period with hydrogen peroxide addition raised the subsequent cyanidation extraction of gold to 88%, giving a tailing assaying 1.5 g/t Au.

Jan 1, 1990

Bolivia, due to its turbulent past with a history of constant military coups, has given an image of complete instability to the foreign investor. The effects of this have been several fold, the major one resulting in a complete lack of exploration in modern terms since their revolution in 1952. What was overlooked by the foreign investor was the fact that revolution produced Agrarian Reform which is the foundation of the stability which Bolivia enjoys today. Another factor that is overlooked is the fact that its past history is one of vast mining fortunes having being made. Their political problems resulted in economic chaos in 1985 with an annual inflation rate of 26,000 percent. This resulted in the collapse of the government but the democratic process continued. Then came the so-called"South American Miracle" in 1986 when the government of Dr. Paz Estenssoro enacted an extremely harsh austerity program which consisted of the abolition of wage and price controls, the abolition of monopolies, the right to hire and fire, the weekly auctions of dollars and the free convertibility of currency which yielded a stable government with 8 percent inflation. This was followed by massive personnel reductions in the various mines and other industries.

Jan 1, 1991

By Greenwood-Smith R, Ellis W. K

A bulk analyser based on the gamma-ray resonance scattering process can be used to give a rapid and accurate measure of the percentage by weight of copper or nickel averaged over a large mass of sample, typi- cally 20 kg. It is shown that for a bulk sample containing about 3 wt.% Cu, crushing to -25 mm is the only sample preparation requited for analysis to within an error of about 0.06 wt.% Cu (errors quoted are one standard deviation). A comparison of bulk analyser and con- ventional assays on the same bulk samples can be used to estimate the sample preparation errors in the conventional methods. The squared deviations between bulk analyser and conventional assays are approximated by the sum of variances in sample preparation, conventional analysis, and bulk sample analy- sis. The sample preparation error was esti- mated as 0.26 wt.% Cu for samples crushed to -2 mm before splitting, 0.08 wt.% Cu for samples crushed to -0.35 mm before splitting, and 0.04 wt.% Cu for the average of 15 grab samples from bulk samples which had been crushed to -2 mm. The average copper grade for each group of samples was about 1.7 wt.%. Results are presented which show that

Jan 1, 1976

Gold-rich porphyry copper deposits areimportant sources of gold in the circum-Pacific region: 26 major deposits contain >7000 tonnes of gold. The deposits occur in a variety of subduction-related settings, and may be underlain by crust that is undergoing either extension or compression and that is either oceanic or cratonic in character. The deposits are associated intimately with composite porphyry stocks, which commonly were emplaced into coeval andesitic volcanic piles. The stocks range in composition from low-K calc-alkaline through high-K calc-alkaline to potassic alkaline. Much of the copper and gold were introduced as components of K-silicate alteration, which may undergo partial overprinting by intermediate argillic assemblages. Advanced argillic alteration is widespread in the shallow parts of the systems whereas sericitic alteration at deeper levels tends to be restricted. Gold distribution generally follows that of copper, which is present mainly as chalcopyrite with or without bornite. The gold is in the native state and occluded by cr in close proximity to the copper-iron and/or iron sulphides. The magmas and metals necessary for the generation of gold-rich porphyry deposits were derived mainly from subcrustal sources, with the subducted slab believed to play a pivotal role.

Jan 1, 1990