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By Keyte SG

Gravity methods of recovering alluvial gold are not very efficient at particle sizes below about 0.1mm. Whereas such gold may not have been economic to recover in the past, the same may not be true today. Centrifugal concentrators, like the Knudsen and Knelson bowls, are showing promise after an inauspicious start, at least in New Zealand. The large proportion of heavy mineral in many auriferous beach sands and the natural hydrophobicity of fine gold should make flotation an attractive contender for its recovery. The conventional mechanical flotation cell is effective, but roughing, scavenging and cleaning are necessary to achieve both high recovery and low mass yield. More problematic is the difficulty of maintaining coarse and dense sands in suspension. The air sparged hydrocyclone is effective at recovering fine gold from a fine Colarado River sand, but is not effective for the coarse and dense beach sands of New Zealand. The flotation column shows much promise for these sands, when recoveries of over 80% and mass yields of less than 1% can be achieved in a single pass. The froth separator of the USSR and flash flotation could also be worthy contenders. It is felt that flotation could be limited to naturally and artificially de-slimed concentrates.

Jan 1, 1990

By Weller KR

A study of high pressure rolls grinding of a number of Australian ores and minerals has been carried out using a pilot-scale machine with rolls 300 mm diameter and 70 mm wide. The results from this study have been used in conjunction with plant survey data to construct computer simulation models of various comminution circuits and these have been used to investigate options for incorporating high pressure grinding rolls into these comminution circuits. Possible rolls options for three of these circuits are presented, and likely energy savings over the existing circuits are discussed together with potential improvements in plant throughput and/or product sizing. A scale-up procedure for predicting full-scale machine performance from small-scale testing is described, and the effects of rolls operating conditions are also discussed.

Jan 1, 1991

By S Hanke, J Burden, P Spies

The Waterview Connection will complete Auckland’s long-planned Western Ring Route, a 48 km north-south motorway alternative to State Highway 1 that bypasses the central city to the west. The project involves construction of 5 km of new motorway – half of it underground in tunnels – to connect the Southwestern (State Highway 20) and Northwestern (State Highway 16) motorways.The Western Ring Route will link the major population and industrial centres of Manukau, Auckland and North Shore to give the region the connected and resilient strategic road transport system it needs to underpin economic growth and sustainable development. It will also provide a direct motorway link between Auckland’s central business district (CBD) and international airport.The project involves construction of twin 2.4 km driven tunnels with an outside diameter of 14.41 m beneath residential suburbs, a major arterial road and a rail corridor. Enabling works began in January 2012 while tunnel construction using an earth pressure balance (EPB) tunnel boring machine (TBM) began in November 2013.This presentation introduces the Waterview Connection project, its role in the development of the Auckland motorway network, its procurement process, the alliance delivery model and an overview of the project’s design features and construction progress to date.Design and construction highlights of the presentation include the TBM start-up, turnaround and breakthrough arrangements as well as the experience gained during the first tunnelling drive. The presentation also covers an innovative process developed for invert construction behind the TBM that is independent of tunnel excavation.CITATION:Spies, P, Burden, J and Hanke, S, 2014. The Waterview Connection Project – progress to date, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 519–540 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By J Kinal, P Steinier

A considerable volume of work exists in the literature examining the electrochemical interactions between grinding media and sulfide minerals. Broadly, most sulfide minerals are more noble than forged steel grinding media used during comminution, therefore a galvanic couple between the media and the sulfide mineral(s) exists, which increases the corrosion rate of the grinding media. The corrosion products of the grinding media, iron oxy-hydroxide species, invariably precipitate on to the surfaces of the sulfide minerals thereby affecting their floatability. This paper explores the science behind these corrosion reactions, and provides an explanation of their impact on the pulp chemistry of sulfide mineral slurries and subsequent flotation behaviour. A number of laboratory and plant case studies are used to illustrate the benefits of changing to a more inert grinding media.

Jan 1, 2005

By Sataev IS, Malinovskaja ND, Otrozdenova LA, Knodov NV, Maximov II, Kuznetzou OK

The technology of flotation recovery of silver from the residue of a zinc plant is described. The peculiarity of this technology is a preliminary pulp conditioning in sodium chloride solution in the presence of aluminum metal under high temperature. In this process the silver is converted to the metallic phase and then floated with the usual sulphydryl collectors. A variant using a combined technology is also described, in which before flotation is performed about 50 per cent of silver is leached. The total silver recovery with the combined technology comes up to 90 - 94 per cent.

Jan 1, 1993

By Swayn G. P, Floyd J. M

BHAS, together with the G.K. Williams Laboratory, and Ausmelt Pty. Ltd., has examined a number of possible alternatives to conventional silver cupellation in gas fired reverberatory furnaces. Of these alternatives, a Sirosmelt furnace was preferred for both technical and economic reasons. Small scale work on Sirosmelt processes was carried out at the G.K. Williams Laboratory at Melbourne University in 1985/86. Pilot scale work was carried out at the Ausmelt plant in Melbourne in July 1987. Board approval for construction of a full size plant was received in October, 1988, and construction of the plant is currently underway. The plant is expected to provide significant savings in operating costs and silver inventory. Hygiene around the furnace should also be greatly improved. An increase in cupellation rate of at least ten times is expected, compared with the conventional reverberatory furnace.

Jan 1, 1989

The first mining in Western Australia probably commenced some 40 000 years ago when Aborigines arrived and began quarrying stone for tools and weapons, and ochre for decoration. The earliest documented mining by European settlers took place in 1850 on a small lead vein in the bed of the Murchison River, reported by the explorer A C Gregory. However, it was the discovery of gold in the Kimberley region in 1885 that first drew wider attention to the State's mineral potential.

Jan 1, 1992

The main aim of the conference is to work towards improved useage of steelplant slags which have largely been considered waste mater- ials, This paper summarised investigations carried out on the suitability of air cooled blast furnace slag, blast furnace granulated slag and basic oxygen steelmaking slag as road base materials. All slag samples were obtained from the PortòKembla Works of Australian-Iron and Steel Pty Ltd. Since road making materials are increas- ingly being characterised by use of resilient moduli, the compressive strengths and resilient moduli were determined for road base of the following slags. 1 Air cooled crushed blast furnace slag 2 mixes of air cooled blast furnace slag, granulated slag, and lime 3 mixes of air cooled blast furnace slag,-granulated slag and basic oxygen steelmaking slag. Evaluation of a local dacite (dense medium grained igneous rock, classification rhyolite), generally considered an excellent road base course material, was carried out for use as a reference material.

Jan 1, 1979

By Brigden J. F, Birrell

A regional geochemical exploration programme commenced in July 1983, based upon low-density sampling of lateritic duricrust over parts of the Yilgarn Block of Western Australia. This resulted in recognition of an area significantly anomalous in chalcophile elements that progressively led to the discovery of the Johnston Range gold deposits in 1985. The deposits, on the Barlee 1:250,000 map sheet, occur in four mineralized zones, and production is expected to commence during 1988. The programme leading to the Johnston Range discoveries was a collaborative research/ applications study between the AGE Joint Venture (Greenbushes Ltd., St. Joe Minerals, and from 1985, Sons of Gwalia NL) and the CSIRO Laterite Geochemistry Research Group (Smith, 1987). It built upon a precursor project sponsored by Greenbushes Tin Ltd that commenced in 1980 and arose from an orientation laterite research project in the Greenbushes rare metal pegmatite district (Smith et at., 1987). Both were multi-commodity programmes and included the search for gold deposits. Basic methodologies for sampling and data interpretation have been described by Smith and Perdrix (1983) and Smith et at. (1984). Continuous geochemical coverage of designated parts of greenstone belts was sought using a triangular grid of 3-km or 1-km spacing, depending upon the expected prospectivity of the areas and the size and characteristics of the ore deposit targets. First-pass sampling, that resulted in the Johnston Range discoveries, was at 3-km spacing and several samples within a 30-km by 5-km area were

Jan 1, 1988

By J Zhou, T D. McGrath, K P. Galvin, C P. Lowes, J J. Eksteen

Pre-concentration of low grade ores can improve the economic and environmental sustainability of an operation significantly, with opportunities for implementation ranging from run-of-mine to mill discharge depending on ore specific characteristics. For a gravity separation, where the performance is fundamentally constrained by mineral liberation, these feeds often represent a very difficult separation given the dominance of the relatively coarse gangue and fine liberation sizes. Thus, building knowledge of the feed through characterisation of the density distribution is critical to assessing amenability before progressing towards lab/pilot-scale test work and full-scale operation. The traditional approach to determining the density distribution typically involved sink/float testing, however, recent developments in hydrodynamic fractionation using inclined channels now offers a more cost-effective alternative with minimal health and environmental risk. A non-hazardous dense liquid, namely an aqueous solution of lithium heteropolytungstates (LST), is supplied as fluidisation to a REFLUXTM Classifier, consisting of a vertical section below a system of inclined channels, operating in semi-batch configuration. Fractionation is achieved by increasing the flow rate incrementally and collecting the particles to form a series of flow fractions. The purpose of this paper is to present this new method in the form of a case study, aimed at assessing the amenability of a low grade gold-bearing sulfide ore to pre-concentration. The robustness in the method is demonstrated through comparison with sink/float data, examining the density distribution and the liberation-limited product grade and recovery achievable. These data are then used as a benchmark to assess water-based continuous gravity separations conducted on the feed using a laboratory-scale REFLUXTM Classifier. This data set is used as the basis for process modelling and empirical validation for the recently established partition surface of the separator.

Nov 10, 2020

By Royle A. G

The paper describes a geostatistical structural analysis of an 80 square mile lease of the Athabasca tar sands. Each step of the analysis is presented with the ultimate objective of condensing the principal structural characteristics of the chosen regionalised variables into the opera- tional form of the variogram model. The variogram model is then used to form kriged local and global estimates, with the corresponding estimation errors.

Jan 1, 1977

By H Fukaya T Miki, J Gamutan

Molybdenum disilicide (MoSi2) is a promising material for thermal applications due to its excellent heat and oxidation resistance. It can operate at temperatures of up to 1800°C as furnace heating elements and protect refractory metals such as molybdenum from rapidly reacting with air to form volatile molybdenum oxides at elevated temperature. In this work, the feasibility of forming MoSi2 on a molybdenum substrate by hot dipping in a silicon-saturated molten metal bath was investigated. This method is simple, predictable and can be used to coat large components and complex parts. It was found that tetragonal MoSi2 can be successfully synthesised on the surface of the substrate after dipping for 15 mins at 1000°C using molten tin (Sn), bismuth (Bi) and copper (Cu) baths. The growth of the MoSi2 layer was fast within the first 15 mins and then gradually slowed down with time. After dipping for 60 mins at 1000°C, the thickness of the MoSi2 layer were measured as 441.5, 19.5 and 13.1 μm for the copper, tin, and bismuth baths, respectively. The MoSi2 coating synthesised in this study provided oxidation resistance at 1150°C by forming a protective SiO2 layer on the surface. The SiO2 layer prevented the sample from rapidly oxidising by inhibiting direct contact between the molybdenum substrate and oxygen in the atmosphere. Compared to conventional methods, the proposed hot dipping method produces a MoSi2 layer more rapidly and at much lower operating temperatures. This makes it a more attractive option for coating large and complex components, with the potential to enable the use of MoSi2 in a wider range of applications.

Jun 19, 2024

SOME 70 miles south-east of the of Auckland lies the town of Waihi-the centre of the Waihi goldfield, at present the mining pride of New Zealand. That the glory of most mining camps is evanescent forms an axiom to which it may be expected Waihi will prove no exception. For the last fifteen years, however, Waihi has been an important gold-silver producer, with an annually increasing output, so that now the area ranks as one of the leading goldfields of the world.

Jan 1, 1911

By DiStefano AB, Dale SG

This paper describes the laboratory study implemented to investigate the application of the subaerial technique to tailings disposal for the proposed Olympic Dam Mine. The results of the study and the resulting design parameters are presented. The subaerial technique of tailings disposal is described and the advantages of the method for disposal in arid climates highlighted.

Jan 1, 1984

By Bruington T, Perkins J, Hutton R

Natural resource developments are among the largest and most challenging projects taking place in the world. They involve capital intensive investment with long lead times and the management of geological, market, technical, operational and financial issues. A clear strategy is required to manage these projects and this strategy is underpinned by a development Philosophy.

Jan 1, 1997

Comalco Limited has recently completed construction of a $50 million kaolin plant at the site of its bauxite mining and industrial minerals operations at Weipa. The plant will produce 100,000 tonnes per annum of coating grade kaolin for the paper industry.Comalco produced the first coating kaolin from the deposit in 1979 on a trial basis. Since then a variety of quality coating grades with specific particle ize distributions and brightness values have been prepared.Extensive drilling and bulk sampling of the deposit over eight years has shown that the orebody is large and of a high grade suitable for the production of premium quality coating kaolins.The processing plant technology was developed by Comalco in association with the European kaolin and equipment producer Amberger Kaolinwerke GmbH (AKW).The Weipa kaolin plant is the first of this size to be built in the Pacific Basin region and it will offer the region's paper-coating mills a stable and reliable source of high-quality kaolin, shipped from an established bulk loading port. The paper provides an overview of the development of the kaolin investment, the nature of the production process and details the project management procedure used for the design, construction and commissioning of the plant. Three areas of significant interest, the gas turbine fired pray dryer, the moving bridge shiploader and the use of aerobelt conveyors on the project are detailed.

Jan 1, 1988

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 Mantsevich M, Ivanov V, Volkov V, Ponomarov G

A new ecologically promising technology for the copper-nickel ore benefication using insert gases and pyrrhotite depression is under consideration. The finely dispersed nickel-containing sulphides and the pyrrhotite are easily oxidised during the process of flotation resulting in deterioration of selectivity and valuable component loss in the tailings. One of the ways to improve the benefication is the flotation of easily-oxidising minerals in an inert atmosphere. In the experiments nitrogen was taken as the inert gas supposing that in the industrial scale operations nitrogen generating, as a by-product of the oxigen production. will be used (Rybas et at, 1989). The most wide-spread mineral in the Norilsk rich sulphide copper-nickel ores is pyrrhotite containing iron, sulphur, nickel and platinum group metals. Up to 30 per cent of the pyrrhotite sulphur is recovered into the nickel concentrate causing the high sulphur dioxide emission in the further pyrometallurgical process of nickel production. This is the reason why the problem of the pyrrhotite removal during the ore concentration should be solved, the critical factor of the problem being the lowest possible nickel content in the pyrrhotite. According to the data of the geological and mineralogical mapping the nickel content in the pyrrhotites of rich ores varies from 0.3 to 1.8 per cent, with the mean value equal to 0.6 - 0.8 per cent. This assures the technological and economical effectiveness of the low-grade pyrrhotite removal during the flotation process.

Jan 1, 1993

Variety among deserts is nearly as great as among other climatic environments. Common to most deserts, and to areas downwind from them, is the dominance of aeolian transport of surface material, at least during some seasons of the year. The result is dilution of local surface materials with varying proportions of chemically uniform fine sand and silt, often imported by the wind from remote areas. Fortunately, desert pavement,.even though separated from bedrock by a meter or more of nearly pure loess, is simply a diluted reflection of nearby bedrock. Infiltration of loess through the surface debris and the rudimentary soil-forming processes in the desert usually preserve the integrity of the pavement. This pavement, or its "downstream" derivatives, provides a suitable sample for exploration geochemistry if proper care is taken to circumvent the aeolian dilution. The simplest and most commonly used method of circumventing the dilution is to use a coarse fraction of soils or stream sediments, discarding or retaining the finer fraction depending upon the magnitude of the dilution. Where the coarse surface debris is composed of rock chips representative of the bedrock sources, the method is successful. Under most circumstances the coarse fraction of the surface material will give a fair representation of gross lithology and will occasionally give an indication of mineral- ization. The major drawback to this approach is that selective weathering and erosion in the vicinity of mineral deposits often lead to the loss of ore minerals into the finer fraction, leaving a coarse residue enriched in feldspar and particularly in quartz; thus, the geochemical signature from a mineral deposit is effectively reduced or completely masked. The second most commonly used method to overcome aeolian dilution, and probably the most effective at present, is to use a heavy- mineral concentrate. This approach presupposes that the chemical signature sought resides in a heavy mineral. Fortunately, the arid weathering cycle is conducive to the formation of a wide variety of secondary ore

Jan 1, 1988

By M M. Hilden, M S. Powell, B Foggiatto

In an environment of decreasing ore grade, increasing costs and uncertainty with respect to commodity prices, the industry could benefit from evaluating alternative technologies and innovative circuit configurations. The flexible circuit approach suggests that the design of grinding circuits can be adapted to changes in feed properties and economic conditions. Advances in modelling and simulation are enabling metallurgists to predict the performance of more complex circuit configurations with increased confidence. Ore variability information and processing costs may be used as modelling inputs to determine the optimum processing conditions at a given time. A case study has been completed demonstrating the value of combining a flexible circuit with a model-based optimisation of the process. Ore properties and equipment performance data obtained in operating plants have been used to model and simulate flexible circuit configurations.This paper explores strategies to introduce flexibility to existing circuit configurations when processing ores with high variability. Multicomponent models incorporated in the model developers’ kit (MDK) allow the simulation of more complex and flexible circuits. This capability enables demonstration of the potential to enhance metal production through adapting processing routes according to the ore type being processed. The simulation of different flow sheet configurations allowed the definition of the best option for maintaining the metal production when treating lower grade ores, highlighting the advantages of flexible circuit configurations compared with a one-process-fits-all approach.CITATION:Foggiatto, B, Hilden, M M and Powell, M S, 2014. Advances in the simulation of flexible circuits, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 391–398 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014