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By A. Drouin, D. Lemieux, C. Chouinard

"A gold bearing pyrite concentrate was treated at the demonstration scale (15 t/d) for the extraction of gold using a cyanide-free process. The pyrite was depressed in the flotation circuit in order to promote the flotation of copper and to achieve a sufficient copper grade to meet the copper smelter criteria. However, the recoveries of copper were 80% and only about 50% for the gold was found in the copper concentrate. The balance of the gold (50%) and copper (20%) contained in the pyrite concentrate as a reject from an overall flotation circuit. The gold grade in the pyrite concentrate is 5.40 g Au/t and copper about 0.77%. About 170 tons of pyrite concentrate were processed in the DST demonstration plant. The concentrate was first oxidized using a fluid bed to produce a calcine. Copper was then extracted as copper sulphate using diluted sulphuric acid. The residual solid was submitted to the DST chlorination process for gold extraction. Thereafter, the gold was recovered from the pregnant brine by precipitation over silica using DST proprietary process. The maximum gold recovery by chlorination was 90%. The average gold recovery by cyanidation of these calcines was 71%.IntroductionDundee Sustainable Technologies (“DST”) has developed a chlorination process as an alternative to the conventional cyanidation process for the extraction of precious metals from ores or concentrates. The technology offers viable and efficient gold recoveries and the ability to handle refractory ores and contaminated material (As, Hg, etc..). The process was successfully demonstrated on hundreds of samples provided by various mines, exploration and development projects and has evolved from laboratory experiment to demonstration at an industrial scale.DST’s chlorination process operates in a closed loop circuit, which implies that no liquid effluents are generated. The chemistry and process design allows precious metal deposits containing base metals to be treated viably. The tailings from the process are inert and non-toxic, sulphide depleted and thus non-acid generating. The efficiency of the process has demonstrated excellent gold recoveries within a fraction of the time needed for cyanidation to obtain similar results. The company completed in 2015 the construction of the first industrial demonstration plant operating with the DST technology. The plant has a capacity of 15 tons per day of mineral concentrate, and the ability to extract gold and silver utilizing DST chlorination technology.DST has tested its chlorination technology at demonstration scale on the refractory pyrite concentrate containing 5.40 g Au/t and 0.8 %copper. This auriferous pyrite concentrate, was by-product of copper concentrate respecting the copper smelter norms, is produced in a country where cyanide is prohibited and refractory to cyanidation. The pyrite concentrate was initially processed successfully (gold recoveries: > 90%) by the DST technology at laboratory (2011: 20 kg) and pilot (2014: 5 tons) scales to extract gold. About 170 tons of this pyrite concentrate were processed in the DST demonstration plant located in Thetford Mines."

Jan 1, 2017

By Pierre Lacombe

"The operation of the Louvicourt Mine will have to rely on stringent grade control and on the optimization of the amount of blocked ore made available per given development effort. All of the above being necessary to obtain the highest throughput at the lowest mining cost.To assist in achieving these objectives, the need for production of a competent fill with short curing time was recognized early by the project partners. As well, operating costs associated with the selected method should be as low as possible while meeting the technical criteria.A feasibility study comparing filling methods showed potential benefits in all aspects of the paste fill use, except for its higher capital costs and increased operational complexity. This last consideration was tackled by the conservative design approach adopted in the flowsheet development of the paste fill plant.Since commissioning of the plant has just been completed at this time, the paper will focus on the feasibility study and its background, the design of the plant and testwork results at pilot plant and plant scale.RésuméLe succès de l 'opération de Louvicourt Mine dépendra d' un contrôle serré des teneurs du minerai et de la maximisation de la quantité de minerai développée par effort uni ta ire. Ces critères devant etre respectés afin d'obtenir le taux de production le plus élevé au coût le plus bas.De façon à satisfaire ces contraintes, les partenaires du projet ont reconnu tôt la nécessité de produire un remblai de qualité tout en maintenant un temps de curage court. De plus, les coût d'opération associés a cette opération se devaient d'être des plus avantageux sans sacrifier l'atteinte des objectifs techniques.Une étude de faisabilité comparant différentes méthodes de remblayage a démontré que le remblai en pâte offre des aspects positifs sous taus les angles, si ce n'est de son coût en capital initial élevé et de sa complexité relative d'opération. Ce dernier point fut considéré de près par l'adoption d' une approche conservatrice lors de la conception de l'usine de rernblai.Puisque la mise en service de l'usine n'a été faite que les détails de l 'étude de faisabilité et ses fondements, 1 'usine et des résultats d' essais obtenus a l'échelle de l'usine seront discutés."

Jan 1, 1995

By J Mauk, J Rowland, S Rabone

Most epithermal Au-Ag deposits in the Hauraki Goldfield are hosted in late Miocene andesites. Broken Hills is an exception, being one of the few economic deposits hosted in rhyolite. Investigation of Broken Hills provides the opportunity to collate structural data that may be compared with that collected from andesite-hosted deposits in order to evaluate the importance of rock type on vein development. The rhyolite host rock at Broken Hills is strongly flow-banded, but this anisotropy does not appear to affect the orientation of mineralised structures. There is a range of structures at Broken Hills: veins, faults, fractures, and large breccia pipes. Veins generally strike north-south, with localised changes in strike and thickness. Slip vectors determined from striations indicate near pure dipslip on the main lode, indicating an extensional tectonic setting. The orientations of vein deflections are parallel to slip vectors. This correlation is common in modern extensional fault arrays where fault growth and linkage produces subvertical deflections in fault orientation (eg TVZ). There are three main types of breccias: 1. Primary breccias related to rhyolite emplacement. 2. Jigsaw type secondary breccias that are that developed during the life of the hydrothermal system. 3. Breccia pipes. Broken Hills was a dynamic epithermal mineralising system.

Jan 1, 2003

Agglomeration for Copper Heap Leaching Agglomeration of ore is a method which can be used to eliminate the migration of fine grained particles throughout a leach heap. Without agglomeration, fine ore particles are able to migration within the heap, clogging flow channels and producing large areas where access of the solution is poor. In order to gain the benefits of agglomeration and improve agglomerate strength even further in copper heap leaching, an economical, acid-resistant binder is needed. However, most binders have been used without any systematic reasoning. A set of novel testing methods were developed, including a soak test, percolation flooded columns, and larger long-term leach columns. The soak test compares the degree of breakdown when agglomerates are subjected to an acidic environment. While the percolation flooded columns and larger long-term leach columns evaluate the flow of leach solution throughout the ore bed. Systematic studies have been completed on a wide range of binders using these novel testing procedures. It was found that for a low grade chalcocite ore, which was rich in silica, from a southwest US mine, polyacrylamides reduced the fines migration the best in the novel soak test. The non-ionic binder, in particular, was found to reduce fines migration as much as 93 per cent. Several of the binders tested were shown to increase the hydraulic conductivities of the agglomerated ore up to 2.5 mm/sec, compared to a hydraulic conductivity of only 0.25 mm/sec when no binder was used. These binders also prevented 'slumping' of the ore, which indicates a decrease in breakdown of the agglomerates. The use of a binder also showed no interference with leaching reactions in long-term leaching experiments.

Sep 13, 2010

By J. Koster

[Boron is an element whose metallurgical possibilities never have been investigated thoroughly, probably because of the difficulties experienced in the preparation of elemental boron and its intermetallic compounds. The southwestern United States contain the world's s largest deposits of boron minerals. In general, the mineral is readily available, and mining costs are not excessive. The most important boron mineral of commerce is borax (sodium tetraborate) however, there are large deposits of colemanite (a mineral having the composition represented by 2CaO 3B2O3 5H2O) in Clark County, Nov. This material was worked in times past by converting it to sodium tetraborate. In recent years the deposits have laid idle because of a mire readily available source of borax in the old lake beds of California.]

Jan 1, 1940

By I Thin, L Morizzi, C Seymour, G Mungur

Olympic Dam has been investigating mine design options for the South Mine Area (SMA), which will continue using the existing sublevel open stoping (SLOS) method. The SMA is an undeveloped mining area, located south of the existing underground mining areas currently in production at Olympic Dam. The SMA study reached the stage where geotechnical inputs were required for stope design, infrastructure location and ground support forecasts. A large database of geotechnical data was collected to inform open pit designs for the ODX (Olympic Dam expansion) project (resulting from 659 drill holes). This geotechnical data has since been reprocessed to align with design inputs required for the SLOS mining method. The result has been the construction of a preliminary three-dimensional mining rock mass model (MRMM) that has been incorporated into preliminary stope mine design and infrastructure layout assessments, which have taken into account the predicted prevailing ground conditions.As with any model, it is necessary to improve the confidence in its predictability; therefore the model must be calibrated. The preliminary SMA MRMM was no exception. First pass calibration was possible with results from underground geotechnical window mapping from exposed rock mass conditions in the lateral development and surface geotechnical holes for ventilation shafts.The SMA project continues to advance and has started a program of resource drilling. Selected holes have been identified that target data limited areas. This will ensure that the data gaps are infilled in order to maintain the required data density required to improve the model confidence. In addition, further underground window mapping in the SMA will provide ‘mine scale drill hole’ data that can be used to either update the MRMM or as part of planned future calibration. Stope performance data from stopes will provide further valuable data for calibration purposes.The proposed paper will present the process and findings that have been followed in order to establish a well calibrated geotechnical model that can be used with an acceptable level of confidence in the ongoing refinements of the mine design and planning process for the SMA.CITATION:Thin, I, Morizzi, L, Mungur, G and Seymour, C, 2016. Building and calibration of a geotechnical model for sublevel open stope design at Olympic Dam, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 523–532 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By P. Dhar, H. R. Kota, M. Thornhill

Precipitated calcium carbonate is used as a filler and coating material in the manufacturing of paper because of its high brightness and light scattering characteristics. However, beneficiated calcite has similar potential, given the fact that the industrial specifications are already achieved. For paper industries, the requirement is that the desired product should be pure and have a brightness of 93 to 95 percent. A very-high-grade calcite deposit of around 92 percent is located in the north of Norway, which is used as the raw material for ground calcium carbonate (GCC) feed for the paper industries. There is a substantial amount of calcite resource, which has pyrite and pyrrhotite as major impurities. These sulfides, even when present in minor concentrations, impart color to the end product (paper). Removing these minerals is estimated to increase utilization of the deposit by 10  percent, which represents several million tonnes of calcite marble. Due to the requirement for environmentally friendly reagents and chemicals by the mineral industry, fatty di-amines are being tested for pyrite and pyrrhotite flotation. The interaction mechanism of diamine with the main components of the ore were studied and optimum conditions for removal of sulfide impurities are outlined.

By Taylor G. H

The Triassic Ipswich (SE. Queensland) coals are of bituminous rank. The more exact rank of individual samples was determined by measuring the reflectance of the vitrinite. While in general the rank of the coals increases with stratigraphic depth, minor reversals, probably related to igneous intrusions, occur.The Ipswich coals form a coherent group so far as petrographic type is concerned. All are comparatively rich in vitrite and clarite, cutinite being the common maceral of the exinite group. The mineral contents of all the coals are comparatively high, clay and quartz being most abundant. The coals appear to be of essentially autochthonous origin, and to have been formed under conditions of fairly rapid subsidence.While the use of the coals is at present restricted to combustion, most have pronounced coking properties, as would be predicted from their petrographic composition and reflectance. However, the high mineral content of the coals would be a limiting factor in their use for coke-making.INTRODUCTIONDuring the last ten years, the Division of Coal Research, Commonwealth Scientific and Industrial Research Organization has carried out an extensive investigation of Australian coals, providing a wide range of analyses of most of the important of them. Special attention has been given in recent years to Queensland coals.Most seams were sampled as a number of subsections, enabling the internal variations, as well as the overall properties, to be assessed. The lenticularity of many of the mineralrich layers may tend to limit the significance of the samples, particularly in respect of ash yield, but although the vertical distribution of mineral matter may vary considerably from one sampling position to another, the lateral variation of the total mineral matter in the whole seam may not be great.Apart from extensive chemical analyses and utilization...

Jan 1, 1963

By H. Yilmaz

A testing method for assessing the shear-bond strength of thin spray-on liner (TSL) on rock substrate was developed at Wits University Rock Mechanics Laboratories. The gap between a 20 mm thick steel ring and a rock core is filled with TSL along the depth of the ring. After the curing of the TSL for a predetermined period, the sample is placed on a base, which offers support to the steel ring and the TSL but not to the rock core. A compressive load is applied on the rock core displacing the core on TSL contact and punching it towards the void in the support base. Shear-bond strengths for different TSL products as well as shotcrete were measured. This paper describes the test set-up and points out the important aspects and procedures during sample preparation and test execution. The test results are also presented and discussed.

Jan 1, 2007

By C. Sykes, E. Turner, M. Wyart-Remy

This paper follows that of the Milos Conf, 2002 and examines the collection and reporting of SDIs in the industrial minerals industry in Europe. It compares the characteristics of the GRI Reporting Guidelines, with its Metals and Mining Sector Supplement with those of the EU DG Enterprise Scheme, launched in 2001. The particular issue of SME's and companies which are not publicly traded is examined. The pros and cons of participating in such schemes is a central theme of the paper. The paper concludes that there and many business benefits for these companies in participating and submitting their data. The European Commission Scheme is strongly recommended for companies in the sector which are SME's and not-publicly traded as well as large firms who are listed on European Stock Exchanges.

Jan 1, 2005

By G. F. Sowers

Excavation bracing is a special structural system. It is built from the top down. The design is controlled by the economical construction of another structure as well as by the movement of the ground beyond the limits of its construction. It serves a number of purposes, all subordinate to the construction of the principal structure. Despite its importance, bracing design and construction is frequently overlooked in project planning, causing delays and expensive changes. Thoughtful planning, good design and resourceful, innovative construction can improve construction safety and save time and money.

Jan 1, 2010

A calibration of the Frantz isodynamic magnetic separator relates the current in the electromagnet and the transverse slope of the chute to the specific susceptibility at which separation is being effected. In addition to providing a rapid measure of the specific susceptibility of minerals and composite grains, the calibration provides a guide to operation of the Frantz isodynamic separator for mineral separation, and to the nature of composite grains. The most sensitive magnetic separation is obtained by using the highest practicable current and transverse slope, and the lowest practicable longitudinal slope.INTRODUCTIONProbably all minerals have a magnetic susceptibility measurable by sensitive techniques. However, magnetic separation between minerals which have low but different specific susceptibilities, and which for many purposes are considered essentially non-magnetic, has only become practicable with the development of the Frantz isodynamic separator.The construction and principle of this highly sensitive separator has been described by S. G. Frantz as an appendix to a description by 'Gaudin and Spedden (1943) of its application to the separation of sulphides constituting mill products.Various publications (e.g. Hess, 1949, Hutton, 1952) refer to its use in separating the mineral constituents of rocks, ores, and unconsolidated sands.As used in this study the Frantz isodynamic separator consists of a vibrating chute mounted centrally between the pole pieces of an electromagnet (Fig. 1). This unit may be inclined in any direction by the universal mounting, and the electromagnet current is continuously adjustable from 0 to 1·5 amperes.

Jan 1, 1957

By Roxanne Scott

Outline ? Overview of Community Investment in the Mining Sector ? Emerging Good Practice: ?Strategic Integrated Community Investment? ? Assessing Local Context: ? Institutional Assessment ? Partnership Assessment Approaches to Community Investment Isolation: No proactive engagement in community development Ad hoc philanthropy: small infrastructure, sponsorships, donations Strategic philanthropy: Community proposes options for development Company decides what to do and carries it out, e.g. building schools, health posts, roads Strategic integrated community investment: ? Aligned with government/community development goals and priorities ? Communities and government involved in decisions and execution ? Focused on training and capacity building ? Partnerships ? Continuation in absence of company support Measured returns on investment

May 1, 2010

By A J. Nick, I I. Townsend, J M. Schuler, J D. Smith, R P. Mueller, L Sibille, K Leucht, J J. Fox

The first steps for in situ resource utilisation (ISRU) on target bodies such as the Moon, Mars and near-Earth asteroids (NEA), and even comets, involve the same sequence of steps as in the terrestrial mining of resources. First exploration including prospecting must occur, and then the resource must be acquired through excavation methods if it is of value. Subsequently a load-haul-dump sequence of events occurs, followed by processing of the resource in an ISRU plant, to produce useful commodities.While these technologies and related supporting operations are mature in terrestrial applications, they will be different in space since the environment and indigenous materials are different than on Earth. In addition, the equipment must be highly automated, since for the majority of the production cycle time, there will be no humans present to assist or intervene. This space mining equipment must withstand a harsh environment which includes vacuum, radical temperature swing cycles, highly abrasive lofted dust, electrostatic effects, van der Waals forces effects, galactic cosmic radiation, solar particle events, high thermal gradients when spanning sunlight terminators, steep slopes into craters / lava tubes and cryogenic temperatures as low as 40 K in permanently shadowed regions. In addition the equipment must be tele-operated from Earth or a local base where the crew is sheltered. If the tele-operation occurs from Earth then significant communications latency effects mandate the use of autonomous control systems in the mining equipment. While this is an extremely challenging engineering design scenario, it is also an opportunity, since the technologies developed in this endeavour could be used in the next generations of terrestrial mining equipment, in order to mine deeper, safer, more economical and with a higher degree of flexibility. New space technologies could precipitate new mining solutions here on Earth.The NASA Kennedy Space Center (KSC) Swamp Works is an innovation environment and methodology, with associated laboratories that use lean development methods and creativity-enhancing processes to invent and develop new solutions for space exploration. This paper will discuss the Swamp Works approach to developing space mining and resource extraction systems and the vision of space development it serves. The ultimate goal of the Swamp Works is to expand human civilisation into the solar system via the use of local resources utilisation. By mining and using the local resources in situ, it is conceivable that one day the logistics supply train from Earth can be eliminated and Earth independence of a space-based community will be enabled.CITATION:Mueller, R P, Sibille, L, Leucht, K, Smith, J D, Townsend, I I, Nick, A J, Schuler, J M and Fox, J J, 2015. Swamp works – a new approach to develop space mining and resource extraction technologies at NASA’s Kennedy Space Center: prospecting, excavation, load, haul and dump for in situ resource utilisation, in Proceedings Third International Future Mining Conference, pp 297–304 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 4, 2015

By S. Ndlovu, M. Malatse

"The Witwatersrand Basin is the heart of South Africa’a gold mining industry. The cluster of gold mines located in the Witwatersrand Basin generates a significant amount of mine tailings, which have adverse effects on the environment and ecological systems. In addition, disposal costs are very high. The exponential population growth in the Witwatersrand area has resulted in pressure on the reserves of traditional building materials. Quarrying for natural construction material is very expensive and damages the landscape. This work therefore examines the use of gold mine tailings in the production of bricks.Different mixing ratios of gold tailings, cement, and water were used. The resulting bricks were then cured in three different environments - sun dried, oven dried at 360°C, and cured in water for 24 hours. The bricks were then tested for unconfined compressive strength, water absorption, and weight loss. The results showed that the mixture with more cement than tailings had a compressive strength of approximately 530 kN/m2. It was also found that the best brick curing system was in a water environment. Bricks made from tailings cost more than conventional bricks because of the higher quantity of cement used, but the manufacturing process consumes less water. Overall, the results indicated that gold mine tailings have a high potential to substitute for the natural materials currently used in brickmaking.Paper written on project work carried out in partial fulfilment of BSc. Eng. (Metallurgyand Materials Sciences)"

Jan 1, 2015

By Gustavo E. Armijo

This job was done in Morristown, NJ, with mono fluid system jet grouting for the construction of a new bank building. After the demolition of the existing two story structures, an excavation in loose sandy fill materials was necessary in order to reach the new structure basement level. Due to this jet grouting was selected as a medium to provide both excavation support and permanent underpinning, minimizing the adjacent building settlements. These two adjacent buildings were partially underpinned with a "gravity wall" made with 2 and 3 rows of secant vertical and inclined jet grout columns. Besides the classical jet grouting control methods, during the jet grouting execution, all the drilling and grouting parameters were recorded by a proprietary system called "Slogger". Additionally, after the jet grouting execution, an innovative result control technique was used by means of the application of the same parameter recording system. Some of the production columns were re-drilled and a comparison was made between the obtained drilling parameters and those obtained for the same age test columns. Under the referred existing conditions and in comparison with the conventional underpinning techniques, this project demonstrated that jet grouting, with proper execution and result control, can be faster than them and can maintain the building structural stability and act, at the same time, as a retention system minimizing the existing building settlements.

Jan 1, 2002

By M. V. Swain, N. Bristow, R. D. Dukino

During mining, crushing and handling the size of iron ore lumps decreases. Key factors in determining the amount and size of fines that are produced are the mechanical properties of the ore. In a continuation of earlier work on the same ores the mechanical properties of three Australian iron ores from Yandi, Koolan and Mt. Whaleback were determined. In particular, fracture toughness was investigated in greater detail by examining its relationship to crack length using the compact tension test. The elastic modulus and strength of the ores were also determined in flexure and compression. The results were interpreted using Weibull statistics, enabling the ores to be ranked according to strength and elastic modulus. These results, together with data on the mechanical response of the ores to stress and observations concerning the effect of mineralogy on cracking, provide a coherent understanding of the mechanisms involved when the ores fracture

Jun 18, 1905

By D N. B Skinner, M P. Simpson

At Ohio Creek, 3 km northwest of the Thames bonanza goldfield, porphyry Cu-Au mineralisation is hosted in a dacite porphyry associated with porphyry intrusion breccias and overlying andesites and dacites. The geological setting is a Jurassic greywacke basement overlain by Late Miocene andesite-dacite volcanics which are extensively altered to propylitic and argillic assemblages. Diamond drilling at Ohio Creek in 1978-1981 by Amoco Minerals intersected low grade Cu-Au (0.12-0.20% C~ 0.23-0.4 glt Au) mineralisation An advanced argillic 'alteration cap containing quartz-alunite¦dickite or pyrophyllite-dickite¦diaspore is centred on the adjacent Lookout Rocks and has potential for high sulfidation Au-Cu mineralisation. There is a zonation from potassic K-feldspar-magnetitealteration at depth in the dacite porphyry, through an overlying phyllic quartzsericite- pyrite zone which is overprinted by pyrophyllite in the overlying advanced argillic cap. Early quartz stockwork veinlets associated with the potassic alteration contain fluid inclusions that trapped a highly saline (50-80 wt% NaCI equiv) fluid at high temperatures (450 to >600¦C) indicative of a magmatic fluid. Some chalcopyrite is associated with slightly later quartz-magnetite veinlets, but the bulk of the copper occurs as disseminated chalcopyrite associated with the phyllic alteration. The potassic alteration is surrounded and overprinted by propylitic chlorite¦epidote alteration. Late polymetallic sulfide-quartz-anhydrite veins occur within and around the margins of the porphyry system as in the Kaiser Reef. Fluid inclusions associated with these late veins were formed at temperatures of about 250-320¦C from low salinity (1-3 wfl~ NaCI equiv) fluids. The spatial association between porphyry eu-Au mineralisation, advanced argillic alteration and polymetallic sulfide veins suggests that they are genetically part of the same hydrothennal system. This is consistent with reconnaissanceK-Ar dates of 11.6-10.7 Ma for the intrusive porphyry at Ohio Creek, alunite in the advanced argillic alteration zone at Lookout Rocks and sericite selvedges from the Waiotahi gold-quartz veins at Thames.

Jan 1, 1998

By Robert M. Funk, James E. Lawver

The development of a laboratory and pilot-scale high-tension electrostatic flowsheet for the production of iron-ore super concentrates having silica contents in the range of 0.1% is presented, A variety of hematite and magnetite ores were tested with this flowsheet, and the pertinent metallurgical data are given. The applications and limitations of this process are brought out in terms of both practical and theoretical considerations. There have been many new developments in the past few years that have required mineral beneficiation engineers to consider new techniques for iron-ore concentration. Developments in iron powder metallurgy, and particularly the making of sheet metal directly from high-purity iron-ore concentrates, and the concept of using metallized pellets as a substitute for scrap in electric-furnace steelmaking have created demands for what is commonly referred to as iron-ore superconcen-trates. In most cases, specifications for superconcentrates are that they contain less than 0.1% total gangue, with some applications requiring less than 0.05% gangue. To produce these concentrates, new and modified processes are being developed, and the three methods receiving attention as the primary concentrating methods are: 1) Magnetic separation in which dry rotor-type equipment is used for magnetite and the high-intensity magnets are used for hematite. 2) Amine flotation. 3) "High-tension" electrostatic separation (or, elec-trodynamic concentration). This paper examines the high-tension electrostatic process in terms of its limitations and abilities for the production of iron-ore superconcentrates. A technically effective and simple flowsheet was developed through laboratory and 5 and 100-ton pilot-plant studies for the production of concentrates containing from 0.02 to 0.20% SiO, with iron recoveries between 85 and 90%. The process is also shown to be economically feasible. Laboratory Test Program Separation Characteristics: The suitability of the electrostatic high-tension method for iron-ore supercon-centration stems from the fundamental mechanism governing the process, i.e., particles are separated on the basis of differences in electrical conductivities. This conductivity is a characteristic property of minerals, and if the difference between the conductivities of two min- erals is great enough, then their separation can be performed by a high-tension machine. As shown in Figs. 1 and 2, the critical factor is the time necessary for the particle charge density, which is established by a corona discharge field, to decay to a level such that the centrifugal force acting on the particle exceeds its electrostatic, or image, force. At this point, the particle can leave the rotor at some trajectory and fall into an appropriate product receptacle. This decay time is directly proportional to electrical conductivity, and the process variables, such as feed rate, rotor speed, electrode configuration, and rotor composition, are selected to optimize the ability of the separator to resolve different conductivities. Table 1 lists the measured conductivities for some of the iron and gangue minerals used in developing the flowsheet. These results were obtained by using the conductivity cell described by Lawver and Wright.' The discharge curve of most minerals that lend themselves to super concentration by high-tension is so fast that the

Jan 1, 1971

A201 aluminium alloy is a high strength casting alloy with a nominal composition of Al-4.6Cu-0.3Mg-0.6Ag. It is strengthened by the O(Al2Cu) phase and the ??(Al2Cu) phase during heat treatment. Further strengthening of this alloy system can be obtained through the addition of transition elements, but care must be taken as other elements might have adverse effects on the mechanical properties. The objective of this study is to determine the influence of Mn on the tensile properties of rheo-processed Al-Cu-Mg-Ag alloy A201. ThermoCalc software was used to predict the different phases that can be expected in the alloys, and scanning electron microscopy(SEM) with energy dispersive spectroscopy (EDS) was used to investigate the actual phases that formed. The influence of these phases on tensile properties is quantified. SEM and ThermoCalc revealed that there is an increased amount of the Al20Cu2Mn3 with increasing Mn. The tensile properties showed that high amounts of Mn do have adverse effects on the tensile properties of alloy A201, especially the ductility. Keywords Semi-solid metal (SSM) forming, alloy A201, intermetallics, Al20Cu2Mn3

Jan 1, 2011