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As mining and extraction processes improve and lower grade ores become economic, mining for most ores have extended to depths beneath the zone of weathering oxidation created over geological history. These deeper openings expose sulphidic formations and reduced mineral species as either primary ore or simply as accessory or gangue minerals in the country rock. This is not new, underground mining for primary base metal and gold have long been familiar with these problems, as have coal and uranium miners. The change is simply that the number of mines exposing sulphidic waste rocks, tailings to the atmosphere and/or leaving behind dewatered sulphidic rock surrounding the mine void has increased the number of sites from where acid mine drainage (AMD) may emanate with consequential problems for the hydrological environment including downstream catchments (Miller et al, 1996). The principles of ecologically sustainable development (Brundtland, 1987) have been more or less ratified by all the developed nations of the world and this has led, amongst other things, to an expansion unprecedented in the research and documentation of means for achieving long-term environmentally acceptable stabilisation of solid wastes of all sorts. These have revealed that AMD problems can be minimised and even reversed in many cases by the integration or co-disposal of biodegradable organic wastes with oxidising sulphidic wastes (Elliott et al, 1996). This paper considers how this might be achieved at mine sites in Australia and the results encountered at some relevant sites.

Jan 1, 1997

By D J. Bradshaw, E M. Wightman, B Newcombe

Flash flotation plays an integral role in many of the gold and sulfide mineral concentrators around the world, and yet despite this widespread use, very little information on this unit process is available in the published literature. For operations to maximise the performance of their flash flotation circuits, understanding how these cells operate, the nature of the particles they target and how to predict whether a flash flotation cell should be used on a specific ore type is of vital importance. This paper provides a summary of the key findings of a large flash flotation research project based in the operating environment of a refractory gold concentrator. The influence of key flotation performance criteria including gas dispersion, residence time and particle segregation within the cell will be discussed and recommendations for process improvements will be made throughout. The nature of the particles within the flash cell will be examined, as will the impact on the type of particles that are passed to downstream processes when the flash flotation cell is taken off-line. The development of a laboratory method to determine whether an ore is suitable to undergo the flash flotation process is also presented for its potential to aid in flow sheet development and optimisation for new ores.CITATION:Newcombe, B, Bradshaw, D J and Wightman, E M, 2012. Into the belly of the flash à Insights into the mechanisms at work within a flash flotation cell, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 163-170 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

Gwalia Consolidated Ltd has been in the mining industry for about 15 years, yet its key wholly owned Greenbushes Mine has a history dating back to the last century. Similarly Gwalia Consolidated's associate, Sons of Gwalia Ltd owns the historic Sons of Gwalia and Marvel Loch Mines with Sons of Gwalia celebrating its centenary this year. This durability is a testament to the quality of the orebodies concerned and the massive technological achievements over this time which have enabled each of these mines to maintain their competitiveness. While Sons of Gwalia and Marvel Loch were and continue to be gold mines, the wholly owned Greenbushes Mine has survived and in fact prospered through the development of alternative products from its rich and unique pegmatite. Similarly, for Gwalia Consolidated to grow and prosper it will be necessary to expand the current portfolio of products and operations. The Greenbushes Mine has already given Gwalia world `No 1' status in both the supply of primary tantalite concentrates and lithium minerals (spodumene). The asset base contributed by Gwalia's gold investments assisted in the recapitalisation of the Greenbushes assets to fully develop their potential. Industrial minerals and strategic metals were of interest to Gwalia as these markets are relatively small and it is possible to develop an influential if not dominant position in the market with a quality asset. Capital expenditure to develop such projects are also usually in the order of $10 m to $20 m, a manageable range relative to Gwalia's size.

Jan 1, 1996

By I Arburthnot, N Lawler, C Loan

The function of a thickener is to optimise and accelerate the process of gravity sedimentation. The desired end product (be that maximised concentrated solids or clarified liquid) determines how the thickener is designed and operated.Significant internal research, together with extensive on-site piloting, by Outotec has resulted in the determination that the application of the appropriate amount and type of shear to hindered settling aggregates can result in a substantial change to the sedimentation process. A new patented technology, called shear enhanced thickening (SET), has been developed. SET results in considerable design implications for full-scale thickeners, including a substantial reduction in required footprint and/or significant increases in underflow density.The development of SET, combined with laboratory and pilot scale verification, will be discussed along with the introduction of this technology to a number of full-scale thickeners. The associated implications and benefits for industrial thickeners are outlined.CITATION:Loan, C, Lawler, N and Arburthnot, I, 2012. Industrial scale results from shear enhanced thickening technology, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 341-346 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

An improved technique for the quick and accurate measurement of the weight and centre of mass in the horizontal plane of large machines has been developed. On-site weighing of large plant such as bucket wheel dredgers is an important part of the commissioning procedure. The results from the weighing assist in determining the stability of the machine and also enable confirmation of the structural weight distribution used for stress analysis at the design stage. In this paper the techniques previously used for weighing are reviewed and the sources of error using these methods examined. A full descrip- tion of the current technique and procedure is given explaining how the measurement system comprising strain gauge load cells, displacement transducers, wind speed and direction sensors, data logger, computer and software was developed to enable quick and accurate measurements to be made. Proposed modifications to software necessitated by the replace- ment of current measuring instrumentation and computer are discussed. A typical example of measurements from the weighing of a large dredger, illustrating the accuracy of the new technique is given and the calibration technique used to check the accuracy of the force and moment measurements is explained. An outline of how the results are used to certify the machine for operation is given.

Jan 1, 1989

By Smith I. T

Mine operators have long recognised that the results achieved in primary blasting are critical to subsequent mining activities. With the introduction of "in the hole" drills under- ground and the advantages offered by the use of water gels in conjunction with ammonium nitrate-fuel oil (ANFO) explosives, new mining methods have been developed and enabled improvements in older methods. Pumpable water gels have been used with varying success underground. These gels allow a high loading density even in ragged bore- holes. The problems encountered with slumping in upholes is recognised so the current trend is to use these gels in downholes where wet holes are prevalent. Cartridged water gel technology has advanced to the point where it has allowed the replacement of nitroglycerin (NG) based explosives and pumpable water gels. Today, gels can be made as a tampable product for use in development headings or as a slump- ing product for downholes to give an effective coupling. With the introduction of the Tovex« pneumatic loaders, the problems associated with a pumpable gel were eliminated and gave the user the ability to alter his loading density.

Jan 1, 1977

The mining. operations of Bougainville Copper Pty Limited are located at Panguna on the Island of Bougainville which is part of the Territory of Papua and New Guinea. Mineralisation in the Panguna area was first established by C.R.A. Exploration Pty Ltd in 1964. Exploration work since then has established ore reserves estimated to be 760,000,000 tons of.0.47% copper and 0.4 dwt./ton gold. An economic feasibility study completed in July of this year has enabled a decision to be made to proceed with a major mining operation. The ore will be mined by open cut methods and will be treated in a conventional concentrator with a nominal capacity of 90,000 short tons per day. The concentrate will be pumped as a slurry through a 15 mile long pipeline to a port established on the east coast where it will be filtered and dried ready for export. Other supporting facilities for the mine include two towns, a 135 megawatt steam power station, and access roads.

Jan 1, 1970

By R Wei, Y Peng

With the depletion of high-quality ores, the efficiency of extracting difficult gold ores through flotation and leaching becomes very important in the mining industry. Iron contaminants, sulfide and carbonaceous coatings on the surface of gold and gold bearing minerals significantly hinder the recovery of gold during gold processing. As the surface of gold minerals is easily contaminated, coatings of iron oxides and iron hydroxides originated from the grinding process and oxidation of iron sulfides will cause a retarding effect on both gold flotation and leaching.To mitigate the processing issues caused by undesirable surface coatings on gold minerals, a new technology in treating surface coatings of iron contaminants has been developed. The pulp potential and pH of the slurry are altered to allow dissolution of surface coatings which are further excluded by the use of complexing reagents. The current work shows that iron contaminants can be removed from the surfaces of gold through Eh-pH adjustment and chelation which result in significantly improved gold flotation response. The addition of complexants aids the formation of iron chelates to prevent the iron species in the solution from forming iron oxide and iron hydroxide in the flotation conditions.CITATION:Wei, R and Peng, Y, 2014. Mitigating the effect of surface coatings on gold processing, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 187–192 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

By N Davies, M J. Coward, P L. Hissey

Mount Isa Mines has four mining operations in Mt Isa with the X41 and Enterprise Mines producing copper and the Lead Mine and George Fisher producing lead zinc and silver. Each stream contributes ore to their respective concentrator at a feed rate and therefore metal ratio set out by the monthly schedule. Mine Planning and scheduling lead to a sales and operating plan (S&OP) and revenue projections which ultimately derives actual revenue /tonne and therefore cost/tonne. At Mount Isa, both the copper and lead/zinc streams produce ore from relatively new operations to be blended with material from more mature operations. It is critical to accurately predict the metal contribution from each operation in order to gauge the relative performance of each mine. Development mining ore contributions are estimated and reconciled, as are stope and bench sources. Performance is continually measured and assessed during extraction and grade adjustments are made to account for underbreak, overbreak and design modifications. It is critical to not understate or overstate the contribution from one operation relative to the other as this can produce a false picture of operational performance. Identifying process improvements are key to improving the business overall. Ore from the lead stream passes 17 measurement stations and two midstream reconciliation points before delivery to the heavy media plant (HMP), where the metallurgical circuit begins. From this point two concentrates are produced. A zinc concentrate for treatment off site and a lead concentrate for further on site processing. The lead smelter takes 100 per cent of Isa concentrates as well as a contribution from BHP-BillitonÆs Cannington Mine.

Jan 1, 2002

By D J. A Van Zyl, J C. Cunning

Technological advances associated with the expanded application of paste technology in underground mine backfilling are now stimulating an interest in the disposal of process tailings as paste in the surface environment. Concurrent with the development of alternative surface tailings disposal practices is the requirement to fully understand the consolidation behaviour of tailings in paste form, and to relate this understanding to the significant body of data and operating experience from decades of study of the performance of hydraulically placed tailings. One effective method for demonstrating the benefits derived from handling and placement of tailings as paste is to review tailings slurry consolidation theory from the perspective of the changes which take place in the material as it makes its transition from a loose slurry to a dense, stable deposit resulting from managed thin-layer deposition. For a typical process tailings, an example is provided which illustrates the effect which mechanical dewatering has in accelerating the consolidation process and thereby providing a range of benefits from the perspective of surface disposal. Increased rates of filling (rise), expanded use of upstream embankment construction methods and elimination of impounded surface solutions are some quantifiable benefits which can be assembled on a site-specific basis to allow for valid comparisons with more traditional approaches to tailings disposal.

Jan 1, 1998

By G T. Hefter, P Singh

The effect of using SO2 as an anodic depolariser in the electrowinning of copper from aqueous acid sulphate solutions has been studied using cells without/with a ceramic diaphragm. In all cases SO2-saturation of the electrolyte/anolyte decreased the anode potential by 68 to 75 per cent largely due to a change in the anode reaction from the oxidation of water to the oxidation of SO2 . However, poor quality deposits and low current efficiencies are encountered if SO2 is allowed free-access to the copper being deposited at the cathode. This situation is easily avoided by using a diaphragm to restrict SO2 to the anode compartment and for these conditions the resultant copper deposits are of a similar (high) quality to those obtained in the absence of SO2.

Jan 1, 1999

Hidden under picturesque Bemic Lake, in Canada's eastern Manitoba, lies a highly fractionated pegmatite orebody, hosting a unique assemblage of minerals. Accidentally discovered in 1929, the orebody had a brief history as a tin producer, but it is now mined by Tantalum Mining Corporation of Canada, Ltd. (TANCO), for its cesium, lithium, rubidium and tantalum bearing minerals. The mine also has potential for mbidium-feldspar, amblygonite, gallium rich mica, and quartz production. This paper describes the geology of the orebody, and its mining and processing. Selective, concurrent, mining and milling of the various products necessitates a high degree of planning and control, and these aspects are also discussed. The introduction of Quality Control and SPC are discussed, for such are the keys to excellence.

Jan 1, 1989

By Pina P, Pereira MJ

The increasing exhaustion of raw materials entails the exploitation of poorer orebodies where the target mineral occurs frequently in a very fine dissemination. Consequently it is necessary to grind more and more fine to achieve an adequate mineral liberation. In other words, it is of fundamental importance to know what size one should grind in order to avoid the following detrimental situations: 1. Excessive grinding - giving rise to the generation of ultra-fine slime particles which may be lost in the ulterior concentration process and simultaneously leading to higher energy consumption. 2. Incomplete grinding - giving rise to insufficient liberation and consequently leading to considerable losses of the valuable components in the tailings. Although this issue constitutes one of the most important steps in mineral processing, little research has been done compared to other processes, mainly due to the fastidious experimental work required. This paper describes a complete and integrated system of image analysis, where some algorithms to determine automatically the degree of li beration, for different levels of grinding, are proposed. These algorithms, mainly based on mathematical morphology theory were tested with images obtained from polished sections of different grain size fractions. Cases studies on a complex sulphide ore from an important copper and tin deposit located in the South of Portugal are discussed. Samples of the unbroken ore are also studied by image analysis to predict the degree of liberation obtained according to the fineness of grinding.

Jan 1, 1993

Developed and built in 1982 for simultaneous bathy-metric and reflectivity mapping of the deep ocean by the Hawaii Institute of Geophysics, SeaMARC II was a breakthrough in sea-floor mapping technology. The design was developed cooperatively by industry and academia, and the system has served as a prototype for a new generation of mapping tools for operation in both shallow and deep water.Research programs using the SeaMARC II system have focussed on basic research into the geophysical evo-lution of the Pacific, ranging from intra-atoll mapping to surveys of the deep-sea trenches. During the past few years most work has been concentrated on detailed investigations of the morphology of mid-ocean spread-ing centers, seamounts, and the subduction zones which surround the Pacific. The detail provided by the high resolution, 10-km wide side-scan sonar images of fault and fold structures, combined with the swath of bathy-metric information obtained simultaneously, allow previ-ously unattainable analysis of seafloor morphology and are leading to development of detailed models for ocean crust genesis and deformation.

Jan 1, 1990

By J A. Cowburn

The high intensity zone within the Jameson Cell is the downcomer. It is largely external and separated from the flotation tank. This, together with operation of the downcomer under vacuum, rather than at elevated pressure and the absence of moving parts, allows ready access to the high intensity zone for measurement and analysis. Experimentation was conducted allowing measurements of recovery for residence times of between 20 milliseconds and ten seconds within the downcomer of a Jameson Cell. The affect of aeration rate on the recovery of different particle sizes was also studied.

Jan 1, 2005

By K J. McDonald

All commercially available zircon sands contain radioactivity sourcing from the decay of trace amounts of contained uranium (U) and thorium (Th). The fine particle size zircons of the Horsham area in the Murray Basin region of Victoria, Australia, contain significantly more (about twice) Th+U than those commercial zircon sands. The marketability of these fine-grained zircon sands is likely to rely on the removal of these radioactive impurities. CSIRO Minerals have been working for some time to develop processes for the removal of the radioactive impurities from zircon. It is generally agreed that it is quite impossible to leach U and Th from zircon, however, the Heat and Leach (HL) process, described in detail in Aral and McDonald (1999), reduces the radionuclide levels significantly. The identified (HL) process aims to leach uranium and thorium selectively from a decomposed zircon. The novelty of the process is that a large part of the leached product can be reconstituted to a low radiation zircon by a subsequent heat treatment. The HL process uses a flux mixture of sodium carbonate and calcium borate to decompose the zircon at relatively low temperatures (900 to 1150¦C) and a weak acid (0.5M HNO3; 80¦C/0.5 h; pulp density ten per cent) to leach the radionuclides selectively. The process leaves the major components (ZrO2 and SiO2) behind with little loss. The HL process for example lowers the U+Th content of a Murray Basin zircon from 1000 ppm to 400 ppm U+Th. Among the radionuclides more U progeny is removed than the Th series radionuclides. This is very significant as the radioactivity of U series is 2.5 times more that from the Th series. Therefore the reduction in the radioactivity level of zircon is more than the reduction in Th+U indicated by XRF analysis. A schematic flow sheet of the HL process is shown in Figure 1. Although the HL process successfully lowers the radionuclide levels in zircon sands, the final product contains significant amounts of sodium (up to 14 per cent Na2O) and small amounts of CaO. By comparison, the sodium content of the commercial zircon sands is in general 2O. Zircon is used mainly as an opacifier in tile glazing where the addition of ten to 15 per cent zircon to a translucent base glaze gives the sanitary white colour to the tile surface. Opacification is the result of the refractoriness of zircon particles at the glaze firing temperatures that is generally around 1050¦C.

Jan 1, 2001

By J T. Woodcock

This paper discusses characterisation techniques that can be applied to complex waste products from metal production and processing operations with the aim of devising treatment methods for upgrading the metal content for recycling. Two waste streams were selected to illustrate the role of characterisation in adapting mineral processing techniques to provide an effective recycling strategy. Waste products chosen were:aluminium dross, which contains metallic aluminium particles in a coarse matrix of many components; and steel shredder sludge that contains copper wire and other metallics in a matrix of plastic and natural fibres, iron oxides, metallic iron, and other compounds. Characterisation methods discussed include chemical analysis (XRF, ICP-AES, and selected specialised techniques), phase analysis (XRD, SEM, TEM, and optical microscopy), morphology (IFESEM), sizing analysis (screening, Cyclosizing, Infrasizing, Malvern sizing), and general techniques such as particle shape, surface area, and porosity determinations. The applicability of these techniques to the waste products is considered in relation to their advantages and disadvantages, and sampling issues.Treatment techniques considered for the two waste products included comminution, screening, air or water classification, simple water leaching, gravity separation, magnetic separation, flotation, and eddy current separation.Tentative flow sheets were developed for the two wastes. For aluminium dross, it was proposed to use fine crushing followed by water washing to remove soluble chlorides and aluminium nitride, and then desliming followed by flotation of the granular fraction to give a metallic aluminium-rich concentrate. For shredder sludge, it was proposed to use wet screening, water classification, and gravity concentration to produce a copper-rich product and magnetic separation to produce a metallic iron-rich product.

Jan 1, 2004

The Prominent Hill copper-gold deposit is located approximately 150 km north west of Olympic Dam, on the southern margin of the Mount Woods Inlier in South Australia. Its discovery in November 2001 resulted from the application of a geological model developed from geological, geophysical and petrophysical data pertaining to the Olympic Dam deposit. The discovery has dispelled the notion the Olympic Dam may be unique, and that another deposit like it is unlikely to be found. The Prominent Hill mineralisation is hosted by haematite-matrix hydrothermal breccias, which have suffered extensive iron-sericite-silica alteration and overprinting. Copper, gold, barium, fluorine, uranium, cerium and lanthanum are all intrinsically associated with the hydrothermal iron. Breccias intrude an east-west striking, fault-controlled sedimentary succession, which is flanked to both the south and north by volcanic complexes. Many similarities between Prominent Hill and Olympic Dam are documented including geological setting, mineralogy, breccia styles, and alteration. Differences relate largely to the nature of the immediate host rocks. The similarities and difference provide key data for improving exploration models for this style of iron oxide copper-gold deposit, both within the Gawler Craton as well as globally.

Jan 1, 2004

By Nilmani M, Malone J, Taylor RN, Floyd JM, Gray NB, Fountain CR

CSIRO staff and University of Melbourne staff and students collaborated in an intense programme of investigation on the CSIRO 50 kg Sirosmelt pilot plant.In two days of operation copper matte converting and zinc slag fuming trials were performed, whilst investigation of the process dynamics and process chemistry was carried out. This exercise is an example of the techniques available for process evaluation, which can rapidly advance the understanding of pyrometallurgical operations by use of a team approach covering a wide range of experiments.

Jan 1, 1985

By D J Williams

Coal washery wastes comprise tailings, finer than 0.5 to 0.1 inn depending on the sophistication of the washery, and coarse reject, typically finer than 50 mm. Subaerial disposal of coal tailings slurry at about 30 per cent solids by mass results in the formation of a delta with an average slope of about 1 in 100, representing one extreme. The ravelling of coarse reject on loose-dumping, results in an angle of repose slope with an angle of about 37" (1 in 1.3), representing the other extreme. The pumped co-disposal of coal tailings and coarse reject results in the formation of an upper delta with an average slope of about to one in ten, between the two extremes. The depositional behaviour of these three waste streams is discussed and compared in this paper. The important depositional and material parameters, and a theoretical description of the processes involved, are also presented. Comparisons are made between the depositional behaviour of the various coal washery waste streams, and natural depositional systems, such as rivers, alluvial fans, and scree slopes.

Jan 1, 1998