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The first steps towards the use of artificial intelligence to manage ground conditions have been made. Millar and Hudson (1993) outline the theory behind the use of neural networks in monitoring rock engineering performance.

Jan 1, 1994

By S G. Hagemann, M E. Barley

The Mt Tom Price deposit is a world-class high-grade hematite deposit in the Hamersley Province of Western Australia with an original resource of 900 Mt of almost pure hematite, averaging 63.9 wt per cent Fe. Petrological and geochemical studies at both the Southern Ridge and the North deposit at Mt Tom Price have identified three hypogene alteration zones between unmineralised BIF and high-grade iron ore: distal magnetite-siderite-stilpnomelane; intermediate hematite-magnetite-ankerite-talc-chlorite; and proximal martite-microplaty hematite-magnetite-apatite alteration zones.Fluid inclusions trapped in siderite within the distal magnetite-siderite- stilpnomelane alteration zone at the North deposit revealed primary high salinity (25.5 eq wt per cent NaCl-CaCl2) inclusions that homogenised between 107¦ and 142¦C into liquid. Fluid inclusions trapped in ankerite within ankerite-microplaty hematite veins in the intermediate hematite-ankerite-magnetite-talc-chlorite alteration zone at the North deposit revealed mostly H2O-CaCl2 pseudosecondary and secondary inclusions with salinities of 22.4 - 25.4 eq wt per cent and 22.9 - 25.9 eq wt per cent CaCl2, respectively. Pseudosecondary inclusions homogenised between 153¦ and 449¦C and secondary inclusions homogenised between 103¦ and 157¦C. Fluid inclusions trapped in apatite within talc-microplaty hematite veins in the intermediate hematite-magnetite-talc-chlorite-apatite alteration zone at Southern Ridge revealed that primary, medium salinity (7.0 - 9.0 eq wt per cent NaCl) inclusions homogenised between 181¦ and 257¦C and primary high salinity (22.8 - 25.9 eq wt per cent CaCl2) fluid inclusions homogenised between 118¦ and 257¦C into liquid. Microthermometric analysis of quartz from quartz-hematite veins from the Southern Batter Fault, Southern Ridge show a complex fluid inclusion history. Primary fluid inclusions consist of: low- and high-salinity H2O-NaCI inclusions trapped at temperatures of approximately 140¦ to 230¦C; vapour-rich inclusions of unknown compositions; and æcomplexÆ salt-rich (Ca, Mg, K and Na inclusions).Secondary inclusions consist of medium-salinity fluid inclusions trapped at temperatures of about 140¦ to 280¦C.A two-stage hydrothermal model is proposed for the formation of both the Southern Ridge and North deposits. Early 1a hypogene alteration involved the release of hydrothermal NaCl-CaCl2-rich (25.5 eq wt per cent) basinal brines (110¦ - 150¦C) from the underlying Wittenoom Formation and directed upward along normal faults and focused within the silica-rich rocks of the Dales Gorge Member, by the shales of the underlying Mt McRae Shale Member and overlying Whaleback Formation. Within the Dales Gorge Member hydrothermal basinal brines migrated laterally within large-scale folds with permeability controlled by shale bands and the NW trending dolerite dyke sets. Fluid rock reactions transformed unmineralised BIF to magnetite-siderite-iron silicate BIF, with subsequent desilification of the chert bands. Stage 1b hypogene involved an increase in temperature of the hydrothermal, CaCl2-rich saline (24 eq wt per cent) basinal brines (250¦ - 300¦C) resulting in formation of hematite-ankerite-magnetite-talc-chlorite alteration and the crystallisation of microplaty hematite. Late stage 1c hypogene alteration involved the interaction of low-temperature (~120¦C) basinal brines with the hematite-ankerite-magnetite mineral assemblage. At the Southern Ridge deposit this process was very intense (ie high fluid flux), therefore resulting in the almost total removal of ankerite and resulting in the increased porosity of the ore. Stage 2 supergene enrichment in the Tertiary resulted in the removal of residual ankerite and apatite and the weathering of the shale bands to clay.

Jan 1, 2005

By Carthew SJ

The early period of South Australia's mining history was dominated by Cornishmen as large numbers of miners and their families migrated to escape closure of the Cornish copper mines. Records show that Carthew families migrated from Kent and Cornwall to South Australia. Those from Redruth, Cornwall, were miners and their family history provides an insight into the condi- tions under which early miners lived and worked. Carthews are one of the oldest surviving mining families in South Australia and their movement pattern has been typical of many other early Cor- nish mining families.

Jan 1, 1987

By G D. Price

The Golden Blocks Goldfield is located in the Slaty Creek area,North West Nelson, about 20 km west of Collingwood. Alluvial gold was discovered in Slaty Creek in 1861. Gold was mined from quartz veins up to 1.5 m thick at nine mines from the 1890s until the closure of the Aorangi Mine in 1911. Total production from the Golden Blocks Goldfield is estimated at 46 000 ounces of gold. The Aorangi Mine was the largest mine, with a recorded production of 27 978 ounces of gold at an average grade of 36 g/t. Quartz veins containing gold and sparse sulphide mineralisation occur in a slightly metamorphosed, complexly deformed over-turned sequence of Lower Ordovician sandstones and shales. Primary gold mineralisation is associated with intensely deformed zones that occur near or at carbonaceous shale and sandstone contacts. Some eighty-five percent of all gold production (39 000 ounces) came from four mines confined to the stratigraphically lowest, most widespread shale unit. The quartz veins exhibit textures consistent with a hydraulic fracturing mode of vein formation with fissure infill vein types predominating over replacement textures. Stylolites of carbonaceous material and recrystallization features within the veins suggest multiple phases of deformation. The lack of wall rock alteration, and low primary fluid inclusion temperatures of 200¦ - 265¦ indicate that the ore fluids were associated with a low temperature epithermal system. A model consistent with similar mineralisation styles observed in Ordovician sediments from Pacific Rim occurrences is presented. The high grades (up to 100 g/t) mined from the upper levels of several mines suggests supergene enrichment processes associated with the Upper Cretaceous weathering surface. The Golden Blocks Goldfield has had no modern exploration. The most recent exploration was undertaken in the early 1980s. There are known acid intrusives in the area, with potential for the application of new models of intrusive-related gold mineralisation.

Jan 1, 2004

Mines in the future deliver a paradigm shift in the way mining, material handling and processing are performed, unlocking significant value through production efficiency, flexibility and lower costs and enabling substantial safety and environmental benefits (V Schweikart). Mines in the future are highly productive, with low production costs and are significantly safer. They operate with a skeleton crew and use intelligent systems that fuse information from field instrumentation and other sources to generate the most efficient operating environment. Automated systems are seamlessly integrated across the mine and across the corporate enterprise. Geological models, long-term and short-term plans create optimised production schedules, suitably generated by the mine simulator. Production schedules are shared with the operations management system for deployment mainly by remotely operated and autonomous equipment. As the schedule is implemented, information is collected and shared with various plans, schedules, models and optimisation programs. This production environment is managed in real time from a æCentral Operations CentreÆ and it is visible across the business providing fast and accurate information about productivity, machine condition and environmental conditions. Central Operations Centres also house teams of subject matter experts that monitor and manage the mines and are able to communicate directly with the skeleton crew in the field. Constraints across the production line are displayed and managed appropriately from this location to maximise throughput. Maintenance is interactive and predictive. Reliability specialists in Central Operations Centres monitor the status of machinery and equipment and adjust maintenance plans and strategies to suit. Mining businesses rely heavily on knowledge workers û people with considerable knowledge and learning û and by manual workers. This new knowledge workforce is a team of associates rather than of bosses and subordinates. Field experts become leaders with tremendous autonomy regarding their work. The former line hierarchy becomes a support structure, intervening only in extreme emergencies; instead of giving orders, they are now removing barriers, expediting resources, conducting studies and acting as consultants.

Jan 1, 2009

By S R. Grano, M Vera

This paper deals with two separate case studies investigating the froth phase performance and characterisation of two industrial rougher/ scavenger flotation circuits. Froth phase performance was quantified using a mass balance approach to estimate froth zone recovery. Measured characteristics of the froth phase included frother solution concentration determined by gas chromatography, and the time taken for an equilibrium froth sample to decay to one-half of its original froth height. The latter measurement is referred to as the æfroth half-lifeÆ and is strongly linked to froth stability. Special methods and techniques developed to preserve frother in solution and to measure froth half-life are briefly described. The frother type in the first case study was a mixture of straight and branched alcohols, whilst the frother type in the second case study was a mixture of alcohols, aldehydes and triethoxybutane. The first case study focussed on a flotation circuit treating a low-grade ore containing only a small fraction of floatable copper sulfide minerals, while the second case study focussed on a flotation circuit treating a higher grade complex sulfide ore containing significant quantities of chalcopyrite, galena, sphalerite and pyrite. It was found that froth zone recovery of valuable mineral generally decreased down-the-bank of the two industrial rougher/scavenger circuits. Moreover, decreases in froth zone recovery significantly limit the overall cell recovery of valuable mineral achievable from the plant scavenger cells. However, the decrease in froth zone recovery could not be linked to the removal of frother from the pulp solution to the concentrate product in the preceding rougher flotation stages. Measurements of residual frother in solution suggested that, approximately, only five to ten per cent of the added frother was removed into the rougher/scavenger concentrate, with the remainder appearing in the scavenger tailings. This finding suggested there was apparently adequate frother in solution in the scavenger stages.

Jan 1, 2005

This paper presents a review of heat illness in mining, including reference to several recent investigations by the author. Heat illness is a collective term, covering the conditions of heat stroke, heat exhaustion, heat cramps and miliaria rubra. Heat stroke is life-threatening and is by far the most serious condition. It is rare in mining, if appropriate control measures are instituted. Heat exhaustion is primarily due to hypohydration, following prolonged sweating in hot conditions. Symptoms include fatigue, headaches, dizziness, anorexia, nausea, vomiting, shortness of breath, or brief syncope. Confusion, ataxia, prolonged unconsciousness or convulsions are strongly suggestive of heat stroke. Heat cramps are painful involuntary contractions of skeletal muscle associated with work in hot conditions. The limbs are usually involved and the spasms typically last a few minutes, during which the affected part of the body is incapacitated. Heat cramps tend to occur in heat exhaustion, when hypohydration becomes marked. Miliaria rubra is a skin rash caused by extravasation of sweat into the skin, as a result of obstruction of the sweat glands. It occurs after prolonged and profuse sweating in hot environments. It can take three to four weeks of sedentary duties, in an air-conditioned surface environment, for the condition to resolve. Heat illness would be unlikely in underground mining, if the thermal environment was sufficiently well controlled by ventilation and refrigeration. This is however, often not practicable. Where engineering controls alone cannot provide sufficient control of risk, the residual risk can be assessed using an appropriate heat stress index. While procedural controls may further reduce the residual risk, it is important to remember that these are less reliable than engineering controls and cases of heat illness may still occur. Procedural controls include the application of heat stress limits, education, hydration, self-pacing, early symptom reporting, medical advice, acclimatisation procedures, air conditioned accommodation, support to achieve a healthy body mass index, and an effective emergency response capacity.

Jan 1, 2005

By R Herbert, M E. Malmstr÷, S U. Salmon

The study focuses on sulfide oxidation processes in unweathered pyrite-rich mine tailings from a soil-covered impoundment in northern Sweden. To simulate the oxygen-limited conditions in water saturated tailings two long-term column experiments were performed. Results are presented for the first 11 months of the experiments at room temperature. The tailings used in the experiments were of two different grain sizes (one coarse grained, in the range 0.02 - 0.6 mm with a grain surface area of 1.86 m2 g-1, and one fine-grained, in the range 0.0015 - 0.06 mm with a grain surface area of 10.00 m2 g-1) and with slightly different mineralogical composition. The S:Fe molar ratio in the leachates (1.0 - 1.5) indicates either that pyrrhotite is the main iron sulfide undergoing oxidation in our experiments, or, alternatively that the S:Fe molar ratio in the leachate is determined by pyrite weathering in conjunction with other processes releasing iron or immobilising sulfate. However, speciation modelling of the leachates indicates that ferrihydrite was close to saturation, suggesting that a ferric oxyhydroxide may have dissolved/ precipitated during the experimental period, thereby affecting the S:Fe molar ratio. Pyrite oxidation rates obtained from the two column experiments during æsteady-stateÆ were 2.25 + 10-13 and 8.45 + 10-14 mol m-2 s-1 in the coarse and fine tailings, respectively. Pyrrhotite oxidation rates, as an alternative, were 2.31 + 10-12 and 1.24 + 10-11 mol m-2 s-1 in the coarse and fine tailings, respectively. Natural microbial activity was confirmed in both the tailings and the leachates; therefore, the obtained oxidation rates are not strictly abiotic. It is thus concluded, based on the experimental results, that tailing heterogeneity will result in zones with different oxidation rates, related to their physical and chemical properties.

Jan 1, 2003

By W J. Bruckard

In Australia, ilmenite is produced from beach sand deposits. These deposits contain varying quantities of the valuable minerals zircon, rutile and ilmenite, along with a variety of other minerals. The valuable minerals are upgraded using combinations of gravity, magnetic and electrostatic processing techniques to yield high-grade products. One of the penalty elements present in ilmenite concentrates is chromium, present mostly as chrome spinels. This mineral is particularly difficult to separate from ilmenite, as the properties of the two minerals are very similar in relation to the traditional separation processes. While the deposits which have been treated in Australia in the past have had only low levels of chromium present, many of the newer deposits contain much higher levels of contamination and, thus, there is an increasing need to develop robust processes to separate chrome spinel from the ilmenite. Flotation, which is a unit process with the potential to solve this problem, has surprisingly received little attention for this application. The literature suggests the research effort to characterise the general flotation properties of chromite (chrome spinel with high chromium content) has been extensive and a substantial amount of data is available. However, the problem of separating a small amount of chrome spinel from a large amount of ilmenite requires a different approach to that from separating chromite from siliceous gangue, which has been the main commercial focus of chromite flotation in the past. Much of the work done has been fundamental in nature and the results obtained are fairly inconsistent, as is the testwork completed at batch and pilot plant scale. While these inconsistencies have been attributed to the variable composition of the mineral, there is little evidence supporting this premise. Just as chrome spinel and ilmenite have similar physical characteristics, the flotation response of both minerals is also similar. This paper reviews the literature relating to the flotation of chrome spinel and presents a considered approach to the development of a robust flotation method to separate chrome spinel from ilmenite.

Jan 1, 2001

By N Robson, E Stephens

Australian mining companies are actively exploring for and developing mineral deposits throughout the world with interests in emerging markets such as Africa, Asia and South America. It is important to understand emerging market risk as this will affect the willingness of mining companies and financial institutions to invest in a country, especially with reference to their key asset, the mining licence or operating/concession agreement. Mining companies looking to develop new projects in emerging markets have different risk profiles than projects in countries such as Australia and Canada. Examples of key risks faced in emerging markets include: political û expropriation, nationalisation, contract frustration, currency inconvertibility, war, terrorism, strikes, riots and civil commotion; and legal û mining legislation, arbitration and dispute resolution, trade agreements. There is a problem in the difference in risk perceptions between mining companies, financial institutions and insurers. This can cause different stakeholders to carry out different evaluations of the risks faced by a project, resulting in confusion about the risk margin attached to any project. In a time where resource nationalisation and energy security are prompting governments to become more involved in the mining sector we run through some recent examples of mining companies that have had problems due to the key risks highlighted earlier. Importance of carrying out the right due diligence to replace perceptions with reality: early identification of risks û detailed due diligence on emerging market risks that may arise will help with their identification and mitigation, make use of companies that can help identify risks and suggest solutions, control the cost of financing û risk margin applied to a project finance loan will be influenced by the risks faced, and risk management and using political risk insurance. There are plenty of opportunities in emerging markets but it is important to recognise the associated risks. Detailed due diligence at an early stage will provide long-term benefits.

Jan 1, 2007

By M BSckstr÷m

Acid rock drainage (ARD), commonly found in vicinities of sulfidic mines, possess properties capable of widely affecting the surrounding environment by acidification and heavy metal pollution. In most ARD treatments, various alkaline sources are used to neutralise the acid produced. Utilisation of highly alkaline fly ashes instead of raw materials is a cost-effective alternative, which lately have become increasingly popular. In laboratory batch experiments, neutralising capacity of fly ash was studied during 20 days. ARD was added to the fly ash once a day, for each increment the liquid to solid ratio (L/S ratio) was increased. At an early stage of the experiment (day 6, L/S ratio 12), the concentration of barium in solution unexpectedly increased by a factor of 50 (from 200 to 10 000 ¦g+l-1). This high concentration also sustained the following two days (L/S ratios 14 and 16) before dropping to the original level. pH showed a slight increase during these observations (pH 12.4 - 12.7). The phenomenon was also observed in a parallel and identical series. In addition to barium, aluminium and strontium clearly increased in the same manner, however not as much as barium. Furthermore, concentrations of chromium and molybdenum noticeably decreased at these distinct L/S ratios (12, 14 and 16). The behaviour of barium and subsequently strontium, aluminium, chromium and molybdenum is only partially understood. The decrease of chromium and molybdenum is suggested to be due to incorporation into the interlayer regions of hydrocalumite (Ca4Al2(OH)12(OH)2+6H2O), replacing the hydroxide groups, which also explains the increase in pH. Moreover, the increase of barium, strontium and aluminium could be attributable to dissolution of the silicate mineral celsian (Ba,Sr(Al2Si2O8)). Alternatively, barium and strontium increase could be explained by dissolution of a Ba,Sr(SO4)-solid solution and aluminium increase by dissolution of hydrocalumite or ettringite.

Jan 1, 2008

By Y Peng, D J. Bradshaw, G Long

As copper reserves deepen, they are becoming increasingly less pure. Penalty elements such as arsenic, antimony and bismuth are occurring in increasing concentrations. Environmental issues with smelters are leading to increases in penalty rates for these elements such that some concentrates may become difficult to sell. Arsenic concentration in Rosebery copper concentrates during 2010 varied between 3000 and 8500 ppm. Arsenic levels above 5000 ppm can preclude import to some customer countries. Optical mineralogy has indicated that arsenic in Rosebery copper concentrates is most commonly associated with tennantite (Cu12As4S13) in solid solution with tetrahedrite (Cu12As4S13). In addition, silver reports to concentrate as freibergite (Cu12As4S13 ). A reduction in arsenic content will therefore lead to a concurrent reduction in the silver content.A literature review by Long, Peng and Bradshaw (2012) indicated that arsenic bearing minerals could be removed using potential controlled flotation. Some success in reducing the amount of arsenic had also been reported using either roasting or chemical depression using reagents such as lime and cyanide. Due to the location of the Rosebery concentrator adjacent to world heritage listed temperate rainforest, the use of a roaster or cyanide was immediately discounted. Lime is already used as a reagent in the Rosebery flow sheet, so could be considered as a potential arsenic depressant.In order to determine a method of separating out the high arsenic bearing minerals, two series of flotation tests were conducted. The first series investigated the effect of pulp potential on the recovery of copper, silver and arsenic minerals; a second series investigated the effect of pH, froth depth and regrind.CITATION:Long, G, Peng, Y and Bradshaw, D J, 2012. Production of a low arsenic copper concentrate at MMG Rosebery, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 347-354 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

Lafayette Mining Limited, a listed Australian company, is developing a polymetallic Project on the island of Rapu Rapu, located to the east of southern Luzon in the Philippines. The Rapu Rapu Project is based on the Ungay deposit, which has proven and probable reserves of 6.0 million tonnes of 2.5 g/t Au, 28 g/t Ag, 1.2 per cent Cu and 2.1 per cent Zn. The Project will produce copper and zinc concentrates from a sulphide flotation plant as well as dore from a CIL gold plant. Average annual metal production over the projected six-year mine life is 9800 tonnes of copper, 14 000 tonnes of zinc, 50 000 ounces of gold and 590 000 ounces of silver. Despite a rich mineral endowment and long mining history, there have not been any significant new mine developments in the Philippines since the early-1990s. The investment climate has been affected by legal challenges to the 1995 mining code, civil unrest in parts of the country, the impeachment of the previous President and community concerns about the industryÆs environmental performance. As a consequence, the Rapu Rapu Project is viewed as a test case û within both the country and the international mining industry û on whether minerals investment in the Philippines is an acceptable business proposition from a risk perspective. Lafayette has faced formidable challenges in managing the development risks of the Project. The major risk areas of the Project for which the company developed strategies include: regulatory, environmental and approvals issues, technical evaluation, project development, social and community issues, land acquisition, and financial and marketing issues. This paper describes the risk management strategies successfully pursued by the company, and which have the Project on track to commence construction in 2003. Dealing with each of the areas in turn, Lafayette sought to develop strategies which either effectively neutralised, minimised or otherwise addressed the key risks most likely to be experienced.

Jan 1, 2003

THE reduction of iron from the ferric to the ferrous state prior to its titration by permanganate or dichromate may give erroneous results in the presence of other reducible metals such as titanium. Stannous chloride and metallic zinc both reduce tetravalent titanium to a lower form, and so increase the consumption of the oxidizing standard: solution. Sulphuretted hydrogen and sulphurous acid do not reduce titanium, but are slow in action and troublesome to manipulate.Sulphuretted hydrogen is considered to be the best reducing agent for iron in the presence of titanium.* In the method to be described the advantages of the H 2S reduction are retained without the disadvantages of using the gas. The reduction is carried out by the action of a metallic sulphide having a solubility product of such a value that the sulphide iom, are utilized as fast as they are formed, and but little free sulphuretted hydrogen is given off.Cadmium sulphide was the first to be tried, but its solubility product (3.6 x 10 - 2~)t was apparently too low. The reduction was satisfactory, but the excess was very difficult to remove. Zinc sulphide (S.P. = 1.2 x 10 - 23) was found to be quite satisfactoryin both respects. The zinc sulphide is preferably used in the form of an emulsion prepared from pure zinc sulphate as follows: About 100 grm. of ZnS047H20 is dissolved in 2 litres of water. H2S is passed until no further precipitate is obtained, the acid formed being barely neutralized from time to time by the addition of ammonia. The precipitation of the sulphide in a slightly acid solution gives a finer emulsion than that prepared in an alkaline solution, and any iron present remains dissolved. The precipitate is allowed to settle and the clear liquid decanted. The precipitate is then shaken up with more water, acidified with a little sulphuric acid, allowed to...

Jan 1, 1922

By J Garritsen, P F. Wells, M Xu

IncoÆs Clarabelle mill currently processes ores from eight mines in the Sudbury basin area in Ontario, Canada. The ore from the Garson mine contains a much higher concentration of arsenic than the other ores. Adding this ore into the feed to the mill has resulted in an increase in arsenic content of the Cu-Ni bulk concentrate to a level that significantly affects the smelter operation, and more importantly the efficiency of Cu-Ni separation in the Matte separation plant. The arsenic occurs mainly as gersdorffite (NiAsS), with a small amount being in the form of cobaltite (CoAsS). Extensive laboratory tests on depressing arsenic in Garson ore flotation have been conducted and two reagent suites have been identified as effective arsenic depressants. One is the so called MAA depressant which is a mixture of magnesium chloride, ammonium chloride, and ammonium hydroxide. This reagent combination was reported to depress other arsenide minerals such as arsenopyrite (FeAsS) and enargite (Cu3AsS4). However, in this study for the first time it has been shown to have a depressing effect on gersdorffite. The other reagent suite, a mixture of triethylenetetramine (TETA) and sodium sulfite, that has been reported as an effective pyrrhotite (Fe1-xS) depressant in pentlandite ((NiFe)9S8) flotation, has not been reported as gersdorffite depressant before. The effectiveness of both reagent suites is more pronounced when the arsenic minerals are oxidised through pulp aeration or the addition of hydrogen peroxide. With a flow sheet consisting of a magnetic separation, rougher- scavenger flotation, followed by regrinding and cleaning of combined magnetic and scavenger concentrate, the arsenic recovery to the final Cu-Ni bulk concentrate was reduced from 73 per cent in baseline test to less than 30 per cent with either reagent suite at no decrease in nickel recovery. The TETA/sulfite reagent combination has the advantage over the MAA suite in that pyrrhotite is also depressed, rather than being activated, and the copper and nickel concentrate grades are therefore increased.

Jan 1, 2005

By H R. Watling, W van Bronswijk

Of the various copper sulfides in the EarthÆs crust, chalcopyrite is by far the most common. This mineral is also the most difficult to leach, with hydrometallurgical extraction processes characterised by prohibitively slow kinetics. While a number of processes, including leaching at atmospheric pressure and temperature, pressure leaching at higher temperature, and bioleaching of concentrates in stirred tanks and whole ores in heaps have been demonstrated to some extent, there is currently no full-scale unit process for the hydrometallurgical extraction of copper from chalcopyrite ores. Titan Resources NL operated a test bacterial heap leach at Radio Hill, Western Australia in 2001, to extract nickel and copper from a mixed sulfide ore that contained significant amounts of chalcopyrite, pentlandite and pyrrhotite. A proprietary mixed bacterial culture was used to inoculate the heap, and the nickel and copper were precipitated from the resultant solution as mixed hydroxides. Although 65 per cent of the copper from the Radio Hill heap was eventually recovered, the rate of extraction followed an unexpected trend, as the initial rates of copper recovery were much slower than column tests had suggested. It was postulated that this was due to dissolved copper precipitating as covellite or chalcocite in the most poorly aerated zones within the heap, ie furthest from the aeration pipes at the base. It was further hypothesised that the lack of oxidants (oxygen, ferric iron) and the likely inactivity of bacteria in these areas limited the re-dissolution of such secondary copper precipitates. In this study the above hypothesis was tested in column experiments using the same mixed sulfide ore and a synthetic leach solution. One set of columns was aerated and another set was operated without aeration. Results showed that precipitation of copper occurred regardless of whether the column was aerated or not. The results suggested that pH of the leach solution played a significant part in the precipitation of the copper. Further column tests revealed this to be the case. These results are described here in detail.

Jan 1, 2004

At the outset I want to thank you for inviting a representative of the Chamber of Mines of South Africa to address you on the subject of mining and its future at this, the 13th Congress of the Council of Mining and Metallurgical Institutions. It is indeed a pleasure and an honour to be here. As many of you will recall, four years ago I, as the then President of the South African Institute of Mining and Metallurgy, had the privilege of hosting and welcoming you to the 12th Congress, the third such congress hosted by South Africa. The late Sir Ernest Oppenheimer, President of the 1930 Congress - the first to be held in South Africa - in his opening address foresaw the mining industry as "the most potent factor in spreading the benefits of civilisation over the sub-continent." We have come a long way since those halcyon days but, as I noted four years ago, it still remains true that mines have been, and will continue to be, the missionaries of development in many, if not most, of the Third World countries. I have been asked to address you on the subject of "mining" and to let my imagination roam widely so that delegates can leave the congress with a broader vision than they brought on arrival. It is a tall order and in my attempt to fulfil it I ask you to cast your minds back 120 years to a sultry, rustic day when the first diamond was discovered in South Africa at the now famous town of Kimberley. At that time the South African economy, predominantly pastoral, was still at subsistence level. Almost overnight the ensuing diamond rush turned the then British- owned northern Cape Colony's semi-desert scene into a hive of mining activity, every prospector bent on making his instant fortune. It was very little different, I am sure, to the gold rushes that hit California in 18+8, Australia in 1851, New Zealand in the 1860s. and the Yukon in the 1890s.

Jan 1, 1986

Hindered settling devices (teeter bed, up-current) are widely used in the mining industry to classify mineral streams into various size fractions and to separate minerals. In the coal industry these devices are extremely successful in separating coal of low densities from shale and pyrite. In the beach sand and in the iron ore industry, this equipment is used to beneficiate minerals either as stand alone units or lately as classifiers in spiral circuits. The challenge that these applications give to metallurgists is to be able to simulate the equipment by using mathematical models with or without the aid of small bench scale tests. In any green fields and many brownfields projects, limited amounts of samples make pilot plant tests difficult. Although there are mathematical approaches available, the accuracy is of such a nature that it can not be used for design purposes. This refers to the use of StrokeÆs law, NewtonÆs and the so called intermediate law as is widely published. Research done by the author indicates that in most applications none of the above laws apply. Using the original data as published by Perry and Chilton (Chemical Engineering Handbook, pp 5-64, 1973) and re-plotting it indicates that the settling velocity of particles is a function of (particle diameter)n where n varies between 1.2 and 1.6 which is different from that predicted by the intermediate law that suggests that n = 1.18. Another way of describing the relationship between the drag force and the Reynolds number is done by iterating between settling velocity and the Reynolds number. This needs more computer time but the accuracy obtained from this does add value to simulations. A small but simple test is suggested to determine the settling velocity of particles to enable metallurgists to determine variations from the theoretical calculations to determine the influence of viscosity and particle shape.

Jan 1, 2008

This paper reviews some of the factors thought to control the formation of supergene gold in the Pacific and its Rim. Discussion of these should lead to reassessment of the economic potential of many areas. In several parts of the world many gold-bearing veins display rich gold values only in the oxidized zone, whereas beneath the present (or ancient) watertable the unaltered vein commonly holds only sub-economic refractory low grade sulphides or arsenides. In the Eastern Highlands of Australia some of the most spectacular concentrations of - gold have been found at shallow depths. For example, Harper (1918) describes the Canton mine in New South Wales which was stoped over a length of 180 metres from the 45 metre level to the surface. The reef yielded gold at 300 g/t in the upper levels, but became gradually poorer at depth. Present geologists of N.S.W. Geol. Survey, G.R. Mcllveen and B.P.J. Stevens, believe that many similar Australian enrichments were formed between the surface and its ancient water table level during the extended period of weathering in the Eocene or pre-Eocene. They concede, however, that further supergene movement of gold may have occurred since the early Tertiary. Large quantities of Mesozoic supergene gold of extreme fineness (Au 99.7%, Cu +òFe 0.3%; Leibius 1885) was found at Mt. Morgan near the Tropic of Capricorn in Queensland. Lower Jurassic sediments cover part of the gossan in a small depression caused by oxidation and collapse of the Main Pipe, thus showing that the supergene gold is pre-Lower Jurassic (Cornelius, 1968). Because the Lower Jurassic landscape around Mt. Morgan was mature with a surface slope of less than 10 (Playford and Cornelius, 1967), erosion would have been very slow. Moreover, once all sulphides had been removed from the ore body the Lower Jurassic environment would have reverted from highly acid to alkaline as it is at present. Accordingly, gold, goethite and 1. Dept. of Geology & Mineralogy, University of Queensland, St. Lucia, Australia,

Jan 1, 1987

The following is a brief summary of the Bulli Colliery and its method of operation when Australian Iron and Steel Ltd. took control.Bulli Colliery is situated about a mile west of the village of Bulli and is some 10 mUes north of the Australian Iron and Steel Company's Steelworks at Port Kembla.The mine is owned by Australian Iron and Steel Limited, who purchased it in 1936 from the liquidators of Bulli Colliery and Coke Works.It is one of the oldest working coal mines in Australia, having been opened about 1858 and has worked more or less continuously since that date.The seam worked is the No. 1, or Bulli, Seam, which outcrops along the escarpment of the Illawarra Range and is generally operated by tunnels, the portal at Bulli being some 440ft. above sea level.The colliery holding is fairly extensive, but the coal seam over a large portion of the area within two miles of the outcrop has been more or less destroyed by an intrusion of basalt.At present there is no coal being worked within a distance of about 21 miles from the surface, the farthest workings being about four miles from the tunnel mouth.The existing main haulage road, for the first two miles from the portal, is not straight; it is very narrow over fairly long stretches and has many changes of grade varying from 3% in favour of the load to 13% against the load.The dumping station and screens are situated close to the portal of the haulage tunnel, and at this point the coal is loaded into railway hopper waggons, which are then hauled by rope to the top of a self-acting incline. The waggons are lowered down the incline, a distance of approximately! mile, the ruling grade being about 18 %.From the bottom of the incline, waggons are hauled by Company's steam locomotive to exchange sidings from whence they are taken by New South Wales Government Railway engine to the Company's Steelworks at Port Kembla.

Jan 1, 1947