Search Documents

By T Hirsi, M Weatherseed, T Ritasalo

Cooling tower design has not advanced significantly in the last decade. Recognising this, Outotec has developed an innovative horizontal outflow cooling tower with increased performance compared to conventional design cooling towers.Outotec® Cooling Towers operate today in applications such as spent electrolyte cooling in zinc plants and for gypsum removal before copper solvent extraction. In such applications the use of this latest design has enabled increased production and lower maintenance costs in the downstream operations.In actual operations, the cooling performance has been confirmed at start-up, and has demonstrated that the towers operate in accordance with the CFD modelling. In the last three years these towers have proven themselves in commercial operation to operate with high efficiency and availability.This case study will outline comparative data, collected over two years at a site where both Outotec and conventional cooling towers are operating. The data shows that Outotec cooling towers require less than half the maintenance time of conventional cooling towers, when adjusted to a total solution flow basis. A close partnership approach with the site has allowed continual development, ensuring high availability and high performance.Experience with previous cooling tower installations guided the development of maintenance philosophies and procedures; this resulted in a design where maintenance intensive components were accessible from the top of the cooling tower. This allows safe access to components and maintenance with little or no downtime.CITATION:Hirsi, T, Ritasalo, T and Weatherseed, M, 2015. Improving cooling tower performance with innovative horizontal outflow design, in Proceedings MetPlant 2015, pp 396–402 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

The cyclone, or centrifugal separator, ,is firmly established in industry as a low cost separator of solids from gases.While it will also separate fluids of different densities, and solids from liquids, its main use is to remove relatively fine dusts from gases whose pr~erties are generally not greatly different from those of air. This latter phase of operation is the one that will be dealt with here.The duty of such a cyclone separating system is to take in a supply of dusty gas and separate it into its components of dust and clean gas as perfectly as possible for the least consumption of pressure head. Any separation at all causes pressure loss and, in general, the greater the separation, the greater the pressure drop needed to effect it. The percentage of dust in suspension which is separated from the gas-dust mixture is commonly called the collection or separation efficiency. Overall or "true" efficiency must take pressure drop into account and may be considered as proportional to the ratio of the percentage of dust collected to the resultant pressure drop. For any cyclone It will vary with different dusts.Many commercial adaptions of the simple cyclone are made solely on the basis of pressure drop improvement, without taking into account the effect on separation efficiency, probably because the latter is so difficult to assess correctly. It appears unfortunate but true that the majority of such adaptions and patent gadgets fitted to cyclones which decrease pressure drop, do have an adverse effect on separation. In other' words, the true efficiency is seldom increased but often diminished.Without a knowledge of what actually goes on inside a cyclone, it is impossible fully to appreciate the real effect of a modification. For instance, it is on record that a cyclone...

Jan 1, 1949

By Hayward P. G

Complex ores, characterised by intimate intergrowths between minerals, have previously been treated by flotation with limited success. The most common problem has been that the liberation size is often finer than the lower size limit for selection flotation. A technique has been developed in which the problem is overcome by the use of a selective agglomeration procedure in which the values are coalesced with oil to a size suitable for flotation prior to introduction into the flotation machine. A complex lead ore was characterised by QEM*SEM mineralogy as having a mean galena liberation size of 15 ¦m. The best recovery of lead at 50 per cent Pb grade by standard flotation was 53 per cent. After application of the procedure, 86 per cent recovery was obtained after a single cleaner step. The oil functions as a bridging liquid in the presence of conventional collectors which render the mineral oleophillic.

Jan 1, 1991

By W Liu, S Gao, D Wei, B Cui, Z Guan, Y Shen

Beneficiation of low-grade fine-grained hematite ores becomes increasingly important due to rapid depletion of high quality iron ore resources. However, fine particles, especially ultra-fine particles, make efficient beneficiation of these ores more difficult. Therefore, methods to reduce the influence of fine particles must be considered to achieve better beneficiation performance. Analysis and systematical beneficiation tests were carried out on an ultra-fine-grained hematite ore slime from washing a fine grained hematite ore. Ore particles were found to be presented in loose soil. While some of the ore particles were agglomerated, they were very fine and contained up to 76.5 per cent -0.023 mm material. In this paper, using a single magnetic separation flow sheet with sodium silicate (SS) as a dispersing agent, a concentrate containing 65.05 per cent Fe was obtained at an iron recovery of 68.58 per cent from the hematite ore slime of 56.65 per cent Fe. The single magnetic separation flow sheet was simple and reliable, the agent SS was effective in dispersing ultra-fine particles. The results are believed to be applicable to similar hematite ores.CITATION:Wei, D, Guan, Z, Gao, S, Liu, W, Shen, Y and Cui, B, 2013. Beneficiation study of an ultra-fine-grained hematite ore slime, in Proceedings Iron Ore 2013 , pp 495-500 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

Revised throughput rates, as a result of current mining methods and tight controls on mine dilution, have dictated a change in metallurgical philosophy at Renison Limited. Emphasis on throughput capacity increases has altered to a reduction in circuit complexity and operating costs. Extensive surveys of the gravity and cassiterite flotation circuits led to several plant modifications between August 1989 and March 1990. The coarse and fine gravity retreatment roughing tables were by-passed, the coarse gravity retreatment roughing tables were re-commissioned, the cassiterite flotation rougher capacity expanded and the gravity regrind cyclones re-configured.

Jan 1, 1991

The Archaeozoic Willyama Complex at Broken Hill has suffered several periods of deformation and metamorphism. New structural and petrological information together with that available from the literature gives a picture of the metamorphic evolution of the Barrier Ranges. Several epochs of metamorphism are recognized, and potassium-argon dating of minerals has been applied with limited success to the resolution of these epochs.INTRODUCTIONAdvancements in the mineral industry at Broken Hill over the past eighty years have been accompanied by a continual striving towards increased understanding of both the geological history of the Barrier Ranges and the environment of the Broken Hill ore deposits. However, although many detailed studies of selected localities and particular-aspects of Broken Hill geology have been carried out recently, the regional geology of the Barrier Ranges as a whole has received little attention from a petrological viewpoint since the pioneer investigations of Mawson (1912) and Browne (1922). There still remains a great need for regional surveys combining field studies of the habits, structures and outcrop relationships of the various rock types with laboratory investigations of their chemistry, mineralogy and microscopic ,fabrics. Recording observations arising from three brief visits to the Broken Hill area during 1959 and 1963 may stimulate further surveys.During one of these visits, the generosity of the Zinc Corporation Limited in providing field transport and geological guidance enabled the writer to collect material and study field relationships and appearance of the various rock types at numerous localities covering most of the Willyama outcrop. A complete study has not been conducted...

Jan 1, 1963

By Xu Z, Hu C

An attempt has been made to investigate the performance of green pellet formation of the Daye magnetite concentrate from the weak-magnetic separation plant. The optimum conditions for the commercial production of green pellets was found through experimental research. The satisfactory size range for balling is 75 ¦ 3 per cent -200 mesh. The suitable moisture content is between 8.7 and 9.1 per cent and the optimum amount of bentonite added is between 1.5 and 2.5 per cent. The emphasis is on the size of the feed materials since the grinding fineness, which can be obtained at the plant, at most is 78 per cent -200 mesh. If the optimum fineness for the pellet formation is above this value, this means that the concentrate must be re-ground before balling. The results from experiments showed that a good quality green pellet can be attained by using materials below 78 per cent -200 mesh, which provides a strong foundation for the commercial production of green pellets.

Jan 1, 1999

By D Bradshaw, E Forbes, M Edraki, M Tayebi-Khorami, E Manlapig

There is an increasing trend in the extraction and development of copper resources from complex deposits. These deposits pose mineral processing challenges, as they often contain low grade disseminated copper ore with high levels of impurities particularly arsenic. Although arsenic is a naturally occurring element, the concentrations of arsenic can be magnified by mining and mineral processing activities. Therefore, while arsenic has no significant market value, its presence in the ore deposit will have production, environmental and human health implications. The mining industry’s approach to life-of-mine planning has improved significantly in recent decades and managing arsenic is not an exception.CITATION:Tayebi-Khorami, M, Edraki, M, Manlapig, E, Forbes, E and Bradshaw, D, 2018. Arsenic pathways in copper mining – sustainability issues and potential solutions, in Proceedings Life-of-Mine 2018, pp 60–63 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 25, 2018

By F Burns, G Peachey

The Hidden Valley process plant has recently undertaken a program to relieve process flow bottlenecks and improve process automation. An environment of cost reduction and restrained capital necessitated solutions that primarily utilised existing equipment and internal resources. Removing bottlenecks relieved pressure from a strained circuit that was unable to maintain consistent performance. Improved process automation firstly stabilised the process, then allowed the circuit to sustainably operate at the expanded capacity limits. These allowed implementation of an operating approach that focused process operators towards identifying and resolving process disturbances in advance. Plant recovery and throughput have markedly improved as a result.CITATION:Burns, F and Peachey, G, 2014. Recent process improvements at Hidden Valley gold mine, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 43–54 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

By Boyling A

United Collieries Pty Limited is an Australian mining company operating one underground coal mine, United Colliery at Warkworth in the Hunter Valley district of New South Wales. Centrally positioned, United Colliery is adjoined by other coal mining operations and is located 80km north - west of Newcastle and 20 kilometres south - west of Singleton. (Fig. 1) High standard road and rail links provide ready access to customers and suppliers.

Jan 1, 1998

By C Bartle

In many operations the use of less electrochemically reactive grinding media in the first grinding stage (for example, rod milling and high aspect ratio SAG milling) is rarely considered. Therefore, in reality a plant may inadvertently be using a 'mixed' media charge. That is, whilst employing inert grinding media during secondary grinding, electrochemically active forged steel grinding media may be used in the primary grinding stage. This paper discusses the impact of such a circuit on the pulp chemistry and flotation response of a refractory gold ore. The Wiluna concentrator has two grinding circuits operating in parallel. Line 1 operates a single ball mill in closed circuit with cyclones, and utilises high chrome grinding media, while the second circuit (Line 2) consists of a rod mill (with forged steel rods) in series with a ball mill, which also utilises high chrome grinding media. The cyclone overflows from both circuits are combined to feed a sulfide flotation circuit. Pulp chemistry surveys were completed around both grinding circuits, and laboratory flotation tests were conducted on the cyclone overflows. The results demonstrate clearly that the rod mill/ball mill circuit operated at significantly lower Eh and dissolved oxygen values, while the percentage EDTA extractable iron was considerably higher, when compared to the single stage ball milling circuit. These variations in pulp chemistry had a marked negative impact on the laboratory rougher flotation response, and suggests that plant performance may be affected.

Jan 1, 2008

Following the Coalbrook Colliery disaster in 1960, Salamon and Munro (1967) established the well known empirical coal pillar strength formula in South Africa. This formula has prevented further violent multiple pillar failures. In 1996, a back analysis of the collapsed and uncollapsed cases in Australia led to the development of the Australian empirical coal pillar strength formulae. The original collapsed and uncollapsed coal pillar database of Salamon and Munro (1967) was updated in 2006. This study introduced various strength formulae for different coalfields and seams in South Africa through back analyses of collapsed and uncollapsed cases. Today, the resultant pillar strength formulae from these previous studies and the behaviour of coal pillars are mostly well understood and applied with confidence. However, it was assumed in the previous studies that the behaviour of pillars is not time dependent; therefore, the formulae established do not provide an associated time to failure of coal pillars. This paper attempts to evaluate the so called 'Geometrical Limits' concept to provide the Australian coal mining industry with a tool to assess the long-term behaviour of bord and pillar workings where the pillars are prone to failure due to spalling of ribs. In order to achieve this outcome, the principles of the safety factor concept and the probability of failure calculated using the coal pillar strength formulae have also been evaluated and practical design examples are presented in this paper.

Nov 25, 2010

By Higuchi K

Intorducing the hypothesis that the cause ,òi spontaneous combustion of coal is depending un the accumulation of heat produced by its oxidation, the authors derived the equation expressing the temperature change in a heap i fine coal. To solve the equation, thermal conductivity, specific heat and rate of heat ,eneration of fine coal (-48 mesh) were measured at various temperatures in the range _'0-65¦C. The equation was solved numerically and the volume of fine coal which would ignite spontaneously was estimated as the function of ambient temperature. Using 170 Kg of fine coal, everal experiments for confirmation were conducted. At the ambient temperatures of 60¦C nd 50¦C, coal began to fire spontaneously brut 00 and 110 hours later respectively. Iii addition to this, the measured t,,rp,i,itures in the coal heap agreed with the ,aLulated ones comparatively well, If more volume of fine coal were used, experi;:ontul ;,eneration of spontaneous combustion from ...,n-, , 1-1 I'd Sill al r..

Jan 1, 1981

Gold mineralisation was first noted in 1983 at the Wapolu Point area of Fergusson Island, Papua New Guinea (PNG) during a follow-up regional reconnaissance program. Subsequent exploration programs through to late 1987 completed 22,147m of costean trench sampling, 553 aircore/RC/diamond core drill holes (16,970.5m total) and metallurgical testwork, predominantly on the Wapolu grid in two mineralised areas.Subsequently in 1988, geostat-istical global and polygonal resources were calculated for the main mineral-ised zones, Didigayagaya and Dagwalala. In 1992, a 'probable total reserve' of 1.9Mf @ 2.4g/t with a 1.2g/t cut-off was calculated for these prospects.

Jan 1, 1994

By R Austerberry, S Green

Highly weathered ground, limited collar options and the need to achieve a desired outcome at the lowest possible cost led to the need to adopt a construction approach that had no established design methodology. The newest ventilation shaft at Mandalay Resources’ Costerfield Operations had to be established to a depth of 30 m through poor ground best described as ‘sticky swelling clay’, some of which was contained within an old backfilled pit.The ability to excavate a traditional presink was not possible due to limited space and the introduction of men into the shaft was to be avoided due to the associated safety risks and corresponding increase in cost. Piling in conjunction with raise boring and remote fibrecrete application was identified as a possible solution that could achieve the desired outcome at an acceptable level of risk.Construction of the piles was challenging and required continual refinement until an acceptable level of productivity could be achieved. Limitations on concrete delivery was taken into consideration to ensure hole stand-up time was acceptable and re-drills were not required. The adoption of a set process from alignment, drilling, concrete placement and testing ensured the desired design was achieved. Mine operators should consider the use of piling as a method of shaft stabilisation for the portion of raise bored shaft that passes through the weathered zone.The importance of quality control and attention to detail through the entire shaft construction process cannot be underestimated as issues such as insufficient geotechnical investigation, pile and pilot hole deviation, concrete and fibrecrete quality, as well as delays in the application of fibrecrete can place the success of the project at risk.This paper outlines key learnings from a client’s perspective with regards to the concept, planning, design, execution and completion of a 3.1 m diameter raise bore shaft through both weathered and highly structured ground at the Augusta Mine.CITATION:Green, S and Austerberry, R, 2014. Piling and raise bore construction – key learnings from a client’s perspective, in Proceedings 12th AusIMM Underground Operators’ Conference 2014 , pp 35–42 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 24, 2014

By A Krishnan, C Garcia, I Luna-Berbesi

The discovery and exploration of deposits are progressively shifting to extremely remote regions and greater depths. As a result, exploration costs and the economic risk of a bad investment increase. Current megatrends in the exploration and mining sector indicate a growing demand for the implementation of automation, digitalisation, and machine learning techniques. The implementation of a multi-sensor-based core logging device (DMT, 2024) was done on 400 m of drill cores to optimise interdisciplinary processes in terms of time and quality, by using interlinked and consistent data in real-time, to obtain reliable predictions that support and speed up decision-making. The results are consistent with the laboratory data previously obtained by the mining company, highlighting the benefits of introducing ANCORELOG into their core logging procedures.

Sep 1, 2024

By Horowitz F. G, Lamb P

As mining operations become larger and more complex, larger volumes of geological, geophysical, and production data must be manipulated and interpreted on a day-to-day basis. Because of the large volume of data, more sophisticated data storage strategies, interpretation tools, and visualisation tools must be used by exploration and mining operations in order to remain competitive. Critical to better practice is an understanding of the basic syntax and character of geological and mining data, expressed in the form of a data model. In the short-term, a data model can be used to implement or evaluate schemes for data storage or exchange. It can be used to evaluate software. In the longer term, a data model is essential to the design of the next generation of software for 3D geological modelling. In this and the related paper (Lin et al, 1995) the data model in use by CSIRO is presented, together with: 1. examples of the use of data transfer in the linkage of existing mining software; and 2. examples of the use of the data model in software design.

Jan 1, 1995

By P M. Ashley, M T. Costelloe

The Mary Kathleen tailings storage facility (TSF) contains 7.1 Mt of uranium mill tailings. This waste repository was rehabilitated in the mid-1980s using a multibarrier dry cover. At the time of mine closure, it was predicted that acid mine drainage (AMD) generation would not eventuate and that uranium, heavy metals and radionuclides would be adsorbed within the tailings and not seep from the TSF into the environment. This study reports on the environmental status of the TSF. Gamma-ray measurements indicate an intact dry cover of the waste repository. However, seepage (~0.5 L s-1) of acid (pH 5.71), saline (0.31 per cent), high conductivity (8.8 mS cm-1), slightly oxygenated (DO 2.6 mg L-1), radioactive waters occurs from the toe of the tailings dam into the former evaporation ponds and local drainage system. Seepage waters are calcium-magnesium-sulfate rich with elevated Fe, Mn, Ni, U and Zn values. Oxygenation of tailings seepages causes the precipitation of Fe and coprecipitation and adsorption of other metals (Pb, U, Y), metalloids (As), rare earth elements (Ce, La) and radionuclides (U-235, U-238, Th-227). In contrast, Ba, Ni, Sr, Mn, P, S, Ca, Mg, Na and K as well as Ra nuclides (Ra-226 and Ra-228) remain in solution until pH neutralisation and evaporation lead to their precipitation in efflorescences and sulfate-rich evaporative sediments further downstream. Dry capping of Mary Kathleen uranium mill tailings has resulted in physical containment of the wastes. The dry cover shows no signs of erosion and radiation levels are within acceptable limits. However, the flow rate of surface seepage from the TSF occurs at a much higher rate than predicted. Also, the neutralising potential and adsorption capacity of the tailings and underlying aquifer were overestimated at the time of mine closure. AMD has developed mobilising metals, metalloids, rare earth elements, alkalis, radionuclides and sulfate from the waste repository into surface water seepages.

Jan 1, 2003

By J Player, P Evans, G Sweby

Achieving quick underground access after the completion of an open pit mine can be critical to maintaining project value and ensuring regular ore feed to the mill. This paper outlines the design and construction for two portals in an active open pit to commence underground development quickly whilst installing appropriate ground control to maintain long term access in an uncertain setting. Implementation of the portal designs was complicated by the change in underground design from hangingwall access to footwall access late in the life of the open pit due to preferable ground conditions. The portal locations did not have easy access for ground support installation integrated into the pit design due to the timing of the underground design changes. Practical implementation of the ground support systems subsequently became a key part of the project. Intact rock strength, rock mass characteristics, gradational weathering / alteration profile and structural information were modelled against pit displacement monitoring as the basis from which the portals were located and ground support schemes designed. Conditions around one of the portals necessitated numerical modelling to estimate the appropriate level of ground control for long term stability. The design was completed whilst the open pit was actively on-going and the portal areas not entirely exposed. The rock mass assessment and analysis for the two portals indicated different ground support scheme capacities would be required. The expected level of control for one of the portals also necessitated the use of monitoring with extensometers and load cells to ensure the rock mass response and ground support scheme performed as planned. Construction of the portals demonstrates the benefit of a considered design process, a plan which allows practical installation of ground support schemes where access is limited, the benefit of ongoing monitoring to ensure performance remains within design limits and the challenges involved working within an active pit with limited floor space.

Mar 15, 2021

This paper reviews rehabilitation, closure, and post-closure management of the Tui, Golden Cross, and Martha Mines, all of which are located in the Waikato Region of New Zealand. There was no requirement for rehabilitation of the Tui mine, which was abandoned in 1973. There was a requirement to rehabilitate the Golden Cross mine. Mining at that site ceased in 1997, and rehabilitation is now well advanced. When first approved, there were some requirements for rehabilitation of the Martha Mine, but when reconsented in 1998, those were extended, and in addition a requirement for post-closure management was included. As a result, a Trust, funded by the mining company, has been established to take long-term responsibility for the site following completion of closure. The different rehabilitation/closure requirements at each of these sites illustrates that we have learnt something from the experiences of the past.

Jan 1, 2003