Search Documents

Traditionally, the Lead Lode at Broken Hill has been represented on presentation plans, cross sections and diagrams in scientific papers as a solid black mass, around which the more 'interesting' and 'structurally useful', wall rocks appear to wrap. Structural analysis of the Broken Hill orebodies has usually turned to these wall rocks to determine the structural history of the mineralisation.This tendency to represent the orebody as a massive single entity is incorrect and the aim of this paper is to illustrate that sulphide orebodies (in this case Lead Lode), are a dynamic part of the mine stratigraphy. They can preserve a great deal of useful structural information that can be recorded with detailed internal mapping.Three main categories of ore type are recognised in Lead Lode; Stratiform ores, Mobilised ores and Metasomatically altered ore. The ore types in these categories occupy or have formed in distinct structural and stratigraphic positions and have clearly recognisable inter-relationships.

Jan 1, 1993

By Baxter D. A

This paper, one of two written about the Queensland Railways Brunswick Street tunnels presented at the VIII Australian Tunnelling Conference, 1993, describes the design and monitoring aspects of the railway tunnels built between Central Station and Brunswick Street Station.The design was mainly influenced by the need to minimise settlement of buildings above the route. The performance of the design details and the monitoring of the tunnels are briefly described.Appendices include extensions to the work of Curtis in the analysis of circular tunnels in a viscoelastic ground.Reference: Asche, H R and Baxter, D A, 1993. Design and ground support monitoring of the Brunwick Street rail tunnels, Brisbane, VIII Australian Tunnelling Conference.

Jan 1, 1993

By M Singh, R C. Steinhaus, J J. Rust

Metallurgical process control systems in mineral plants often employ state-of-the-art monitoring analysers in an attempt to optimise plant operations and enhance mineral recoveries. These systems are unfortunately invariably fed by simplistic ‘sampling’ designs consisting of various in-stream methods or pressurised probes. These are unfortunate compromises and provide a false picture of what a mineral flotation or other process can achieve. The situation is further aggravated by some manufacturers using misleading marketing to suggest discrete cross-stream methods for metallurgical accounting and unreliable continuous in-stream off-takes for control sampling and that they are of synonymous integrity.Reliable, absolute or representative samples are often absent in many modern day concentrator plants, due to compromises around sample taking, particularly in terms of delineation and extraction errors and thus leading to sample bias. For more reliable information from online analysers we need a continuous, but much more reliable sample taken, than is current practice.Online analysers require a fully proportional and continuous supply of sample for effective process control, otherwise maximised or benchmark recoveries will be nothing but a pipe dream. Large discrete cross-stream samples from mechanically less reliable equipment cannot be used as feed to online analysers, as it will negatively impact real-time feedback and efficient process control.It is possible to build correct sampling systems that could do both process controls online and metallurgical accounting at the same time. Multotec Process Equipment (Pty) Limited, in close association with experienced sampling consultant Francis Pitard, have jointly patented a concept to achieve this and which is embodied in the design of the unique Rotating Cone® Sampler (International Patent Application No. PCT/IB2016/057464). This versatile unit for dry and wet applications has high division ratios via two-step sampling and division.A prototype was built and tested to validate the design and levels of precision achievable when employing the unit to split dry mineral fines or even certain foodstuffs.CITATION:Steinhaus, R C, Rust, J J and Singh, M, 2017. Does process control sampling always have to be a compromise?, in Proceedings Eighth World Conference on Sampling and Blending , pp 197–202 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2017

By Hebblewhite B, Humphreys D

An experimental mining project has been carried out in the Collie Basin to demonstrate the safe operation of total extraction mining techniques in the underground mines of the basin. To achieve this, it was necessary to design and install a means of controlling or removing groundwater so that goafing of the overlying strata could be safely achieved as part of the mining operation. The site chosen for the experiment was a triangular panel adjacent to Western No 6 (WD6) underground mine, which includes the 3 to 4 m thick Wyvern Seam beneath 130 to 180 m of overburden. The test area abuts a major fault on the downdip side. The overburden and underburden sequences include several horizons of permeable sandstones which form major aquifers. Water problems have long been recognized in all underground mines in the Collie Basin, and have previously prevented the successful application of total extraction mining. Following extensive hydrological investigations, dewatering and depressurization systems were designed to dewater the immediate roof aquifers and to depressurize aquifers higher in the sequence and in the floor. This would enable stable roof conditions to develop and controlled goafing to be achieved. The roof dewatering/depressurization procedure involved a combination of in-mine vertical roof drainage holes and conventional dewatering bores constructed from the ground surface above the mining trial area. The dewatering system was installed and operated for 29 months before the commencement of mining. Mining was eventually successfully completed in two trial panels using a retreat Wongawilli extraction system using bridge conveyors and continuous miners. Water inflow into the mine workings was channelled to a constructed sump area at the lowermost corner of the panel and pumped to the surface via vertical sump bores. The dewatering and depressurization measures adopted were successful in permitting the first controlled and systematic total extraction recovery of coal from the Collie Basin. This trial mining exercise demonstrated the potential for increasing substantially the recovery of coal from the Collie Basin, where previously recovery rates of around 30 percent from underground mining were commonplace, using only bord and pillar methods.

Jan 1, 1988

By T Muzondo, C Prins, D De Vaux, R Schouwstra

The Mogalakwena Platinum Mine in the northern limb of the Bushveld Complex is Anglo American PlatinumÆs only open cast operation exploiting the Platreef. The Platreef, which extends along the basal contact of the Bushveld Complex, is geologically and mineralogically a much more complex orebody than the Merensky and UG-2 reefs. Changes in the footwall and the genesis of the Platreef translate into a number of rock types being present. These rock types vary in hardness and recovery potential and present challenges to metallurgical staff trying to optimise the concentrator. A true understanding of the implications of treating these rock types is required if the maximum value from this orebody is to be obtained.In order to more accurately forecast production and incorporate ore variation in the mine plan and comminution and flotation circuits, a geometallurgical approach to managing the operation has been used and is being further developed.CITATION:Schouwstra, R, De Vaux, D, Muzondo, T and Prins, C, 2013. A geometallurgical approach at Anglo American PlatinumÆs Mogalakwena Operation, in Proceedings The Second AusIMM International Geometallurgy Conference (GeoMet) 2013 , pp 85-92 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 29, 2013

By D Capstick, M B. Ebell

This paper describes the test work, process design, commissioning and operation of a processing system at the Ergo gold operation that improves the extraction efficiency from gold tailings material. The improvement in recovery is derived from the separation of the gold contained within the sulfides of the tailings material and a dedicated process stream to recover that gold.The sulfides are separated by means of a flotation circuit and that resulting concentrate is subjected to a regrind of below 20 ¦m to enable a greater liberation of the gold. The ultra-fine material is then subjected to a dedicated leach circuit to recover the now exposed gold particles.The case study is an example of the challenges of introducing new technology and methodologies to a well-established operation and thereby attaining improved efficiencies and tangible business benefits.CITATION:Ebell, M B and Capstick, D, 2013. Improving extraction efficiency from Witwatersrand gold tailings using flotation and ultra-fine grinding of concentrates, in Proceedings World Gold 2013 , pp 301-306 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 26, 2013

By B Yeganeh, A Sam, A Kohsari

The base of separation at Gol-e-Gohar iron ore plant (Sirjan in the south of Iran) is magnetic separation after milling. Magnetic separation in the plant is divided into two parts: dry magnetic separation and wet magnetic separation. Sixty-five per cent of the plant production belongs to the dry magnetic separator section. Therefore, investigation of this part of the plant is necessary. Prediction of plant production is one of the most important subjects in mineral processing plants. That means, before feed enters the plant, specification of production has been calculated with laboratory methods. The purpose of this paper is the prediction concentrate quality has achieved from the dry magnetic separator. The content of iron in the final dry concentrate will be predicted, with laboratory, pilot and modelling methods, before feed enters the plant. Different variables are used in this approach, which consist of: speed of the first dry magnetic separator (rougher), speed of the third dry magnetic separator (cleaner), iron content in plant feed, size of 80 per cent passing of feed, size of 20 per cent passing of feed and iron content in pilot dry magnetic separation concentrate that performs in a standard manner. The artificial neural network is used for modelling and one of its branches is the radial basis network (RBN). Iron content in magnetic separating concentrate in plant will be introduced as the target and will be calculated with the RBN method. In the RBN method, a set of data enters to neural network and they will be trained and simulated. Finally, the target will be predicted. Ultimately, the original target (actual iron content) and the predicted target (predicted iron content) compare and error of them will be calculated. The obtained result is acceptable and satisfactory.

Jan 1, 2007

Mt Todd lies towards the south end of the Pine Creek Geosyncline, sandwiched between the Cullen Batholith and the Edith Falls Basin, in an area of regionally metamorphosed sandstones, siltstones and shales. The Batman deposit, some 3 km west of Mt Todd is a sheeted quartz vein system hosted within greywackes of the Palaeoproterozoic Burrell Creek Formation (Finniss River Group). The gold-bearing quartz veins, trending 010¦-020¦ and dipping 60¦-70¦E, are commonly 0.5 to 5 cm wide and occur at intervals which are from 10 cm to 1 m apart. Gold tends to be restricted to the quartz veinlets and immediately adjacent country rock. Grade Control utilises two 4 m 'collar' samples which are collected from each 8 m production blasthole. The irregular distribution of the quartz veins and erratic gold mineralisation has resulted in a disseminated 'salt and pepper' type of gold occurrence, with only a poorly defined footwall. Delineation of ore and waste blocks for mining uses an approach which combines the smoothing effect of kriging with a pragmatic view of the raw data. Large ore blocks with simple geometry help to minimise mining dilution, reduce block variance and give good reconciliations to interpreted ore tonnes and grade. Daily mine face advance is reported against truck counts and provides continual comparison with budgeted production. All data processing uses Gemcom software, together with Lotus spreadsheets.

Jan 1, 1994

By S Maritsa, E K. Chiw, S M. Masuka, ika, T Chisahwira

The challenges facing the iron and steel industry on a global scale include depletion of resources, excessive energy consumption and CO2 emissions. The demand for iron products in Zimbabwe is increasing due to massive infrastructural development like the expansion and improvement of mines, transportation systems and water reticulation systems. In Zimbabwe, cast iron is mainly produced from recycling scrap metals. However, there is currently a shortage of scrap, which has resulted in the vandalism of state-owned properties such as bus terminals and railway wagons and lines. Nevertheless, Zimbabwe is rich in limonite ores, which are idle, and it is the aim of this research that this ore be effectively used to produce feed for the blast furnace. The Blast furnace is still the dominant route for producing cast iron where sintering and coking processes are the main routes for preparing the Blast furnace feed. Sintering limonite ore fines produce a product of poor grade because of the high value of loss on ignition that has a negative impact on Blast furnace efficiency. Furthermore, the sinter plant and the coke making plant are a source of huge environmental pollutants. Since low-grade Zimbabwean coal fines are also available in abundance, they were used in the preparation of the composite materials ensuring maximum utilisation of this resource. Results showed that the limonite ore-carbon composite pellets sample with the binary basicity ratio (CaO/SiO2) of about 0.27 and coal addition of 2.5 wt per cent achieved above the minimum physical quality requirements for pellet of drop number of at least 4, a dry compression strength greater than 2.2 kg/pellet and an indurated compression strength greater than 250 kg/pellet. Limestone was used as the binder avoiding the addition of more impurities from bentonite since the limonite ore has a high SiO2 content of about 8.78 wt per cent.

Sep 18, 2023

By T Mattiske

The Fimiston Open Pit (commonly referred to as the æSuper PitÆ) is a part of the Kalgoorlie Consolidated Gold Mines Pty Ltd (KCGM) operation in Kalgoorlie-Boulder. KCGM manages the Fimiston Open Pit, the Mt Charlotte underground mine, the Fimiston Mill and the Gidji Roaster for its Joint Venture Owners, Newmont and Barrick Australia. KCGM produces up to 850 000 ounces of gold per year. The KCGM operations are located on the historical Golden Mile on the outskirts of the City of Kalgoorlie-Boulder, about 600 kilometres east of Perth Western Australia. This traditionally underground mining centre has been worked since 1893, yielding in excess of 50 Moz of gold from ore with an average head grade of 10 g/t. This represents approximately ten per cent of the gold produced in Australia and one per cent of the gold produced in the world. The Fimiston Open Pit is essentially an aggregation of what were known as the Judd, South, Paringa, Croesus/Eclipse, Central, Brownhill, Drysdale, Morrison, North and Horseshoe pits into one continuous large-scale operation. The old Fimiston Underground Operations (included the Main, Croesus, Chaffers, Lake View, and Perseverance shafts) were also located within the area of the Fimiston Open Pit. The underground operations closed in 1992 due to high mining costs.

Jan 1, 2002

By B McFadzean, N P. Lima, D A. Deglon

The reverse flotation of Itabirite iron ore is typically performed after a desliming step in which most of the sub-10 µm particles are removed. This is done to limit processing problems such as poor flotation recovery of SiO2 due to slime coatings and increased slurry viscosities, unmanageable froths and increased losses of hematite particles due to entrainment. However, the rejection of ultrafine particles contributes to large losses in iron recovery and may contribute to the instability of tailings dams. The aim of this study is to decouple the effects of ultrafine particles in the pulp and froth phases to better understand the processing capabilities of the fines fraction. The flotation test work was performed in a special-purpose continuously operated laboratory flotation cell that has a deep froth section to simulate plant-scale froth conditions. Five conditions of fines addition were investigated at three different froth heights and a solids concentration of 50 per cent. The behaviour of the pulp and the froth were decoupled using froth stability and froth recovery tests. This showed that, even though there is an exponential increase in froth stability at increasing fines quantities, the performance of the pulp has the overriding effect on the overall SiO2 recovery. Pulp zone, froth zone and overall SiO2 recoveries showed that overall recoveries increased by about 3.6 per cent for every 1 per cent decrease in fines content. This meant a large increase of 20 per cent in SiO2 recovery when going from undeslimed to deslimed feed. This was driven largely by increases in the pulp zone recoveries, which were about 4 per cent for every 1 per cent decrease in fines content. The froth recoveries, on the other hand, decreased by between 0.75 per cent and 2.5 per cent for every 1 per cent decrease in fines content, depending on froth height. This paper explores further insights into iron ore flotation processing at different slimes concentrations.

Aug 24, 2022

By R Fanni, D Reid, M Kulessa

Recent updates to Australian industry guidelines emphasise the importance of the assessment of liquefaction potential of tailings. This includes assessment of the cyclic liquefaction potential, and the post-seismic strength of tailings expected to undergo strength loss from seismic loading. Despite this increase in focus, a relatively small number of Australian tailings appear to have been characterised through cyclic and post-cyclic testing. This paper presents the cyclic characterisation of four Australian tailings, consisting of iron ore, lateritic nickel, vanadium and bauxite residue. Material was obtained either from surficial tube sampling or through remoulding samples in the laboratory from slurries. Testing consisted of monotonic, cyclic and post-cyclic tests for each material. For three of the materials, laboratory-scale shear vane testing was also performed to provide a comparison to post-cyclic strengths from direct simple shear.The results indicated cyclic resistances consistent with the results of other tailings presented in the literature. The lateritic nickel tailings provided the greatest cyclic resistance of the four materials tested, followed by the vanadium tailings. This was somewhat consistent with expectations for material behaviour based on index properties. Post-cyclic strengths were seen to decrease as cyclic strains increased, consistent with typical observations in the literature. Following significant cyclic straining, in some instances the post-cyclic strengths approached those obtained through residual shear vane testing. This provides further insight into the strain-dependent nature of post-cyclic strengths for some materials. The implications of these observations on the post-seismic stability condition are discussed.CITATION:Reid, D, Fanni, R and Kulessa, M, 2015. Cyclic and post-cyclic behaviour of four Australian tailings, in Proceedings Tailings and Mine Waste Management for the 21st Century, pp 207–214 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 27, 2015

By A Ross, B De Rivaz

The results of full-scale tests on precast segment made at University of Roma are presented. The segments were cast using fibre-reinforced concrete produced without any traditional reinforcement, by using fiber made in high-strength steel and a new type of anchorage.Bending tests were performed in order to check the bearing capacity of the segments under the flexural actions; these occur during de-moulding, handling, storage phases as well as in the in situ condition (due to asymmetric soil pressure). Furthermore, point load tests simulating the TBM thrust were performed, in order to study the construction phase (excavation).The results show that the segment response largely respects the material testing and design advice according to the Fib Model Code 2010. Providing engineers, precast operators and builders confidence in material strengths and design methodology.CITATION:De Rivaz, B and Ross, A, 2014. Full-scale tests on precast tunnel segments made in concrete reinforced with high-strength steel fibres, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 469–476 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By D Price

Mining at the Tuckabianna Mining Centre in the Murchison district of Western Australia ceased in 1997, after the production of 550 000 ounces of gold at an average grade of 2.5 g/t from 22 separate open pits (Tectonic Resources, 2006). Like many historic mining camps in WA, Tuckabianna was considered exhausted of gold, such that an economic project could not be sustained on the existing resources. Since 1997, three separate companies have owned the Tuckabianna leases. Each of these companies completed minor exploration and some form of mining study to determine if mining could be sustained. All three companies concluded that the remaining resources were insufficient to support an economic project. Silver Lake Resources acquired the adjacent Tuckabianna, Comet and Moyagee projects in 2007 with a combined resource base of 693 000 ounces of gold in 11 separate deposits. In September 2009, Silver Lake commenced exploration in the Murchison targeting extensions to the main resources at the three project centres and completing targeted regional exploration across the lease holding. At the same time, a detailed evaluation of all historic drill data was completed and all resources re-estimated. This has culminated in the resource base increasing to 1.5 million ounces of gold in 20 separate deposits, with two new discoveries being made. In August 2010, a mining feasibility study was commissioned. Preliminary results from the study indicate that an economic stand alone project can be sustained for a minimum of five years. The ability to bring the remaining resource from a once unloved project into production is due to a number of factors: historically high gold price, combining adjacent projects into a single operation, evaluation of all resources regardless of size and grade, and well funded exploration directed to both resource extensions and new discoveries. Using the Tuckabianna Project as an example, this paper attempts to outline the strategy Silver Lake used to define the resources to justify the capital expenditure required for production, and give a summary of some of the successes and failures made as the projects progress towards mining. Examples of where being too rigid and over exuberant have resulted in less than optimal use of expenditure are used to high-light the difficulties in exploring in mature terrains. Evaluation of the success of a company’s exploration strategy at all scales from project acquisition to target selection is critical to the success of future project development. This paper has been part of that process for Silver Lake with some interesting discussions and insights being made. It is hoped that some of the points discussed can be applied to other projects to help achieve the best outcome from the assets available to a company.

Aug 22, 2011

By H Kurth, L Balzan

On-belt analysers have been used since the early 1980s in the coal sector to measure ash content in real time for diverting material on conveyors to remove waste, bypass beneficiation and allow suitable material to proceed to the wash plant for processing. Since 2008, a GEOSCAN-M elemental analyser has been used on an overland conveyor in South Africa to divert direct-shipping quality iron ore to bypass a jig plant. This paper focusses on recent evaluation work to determine the suitability of an on-belt analyser to upgrade the processing plant feed in a copper-gold operation.Copper-gold ore samples from New Gold’s New Afton Mine near Kamloops, BC, Canada were tested to assess measurement accuracy over short time increments. A two-minute measurement increment has been used in the minerals sector as a compromise between good measurement accuracy and a useful tonnage (haul truck equivalent size or smaller). At New Afton, this increment represents approximately 35 t of material. Segregation decisions are currently made after visual and sometimes analytical determination, at increments of approximately 500 t to designate material as ore or waste at the drawbell in the cave.Results of test work including the composition range and expected accuracies by element are shown. The operation, which is not mine constrained, was evaluating the potential for ore upgrading through waste and low grade increment diversion to upgrade ore quality feeding the mill. Prompt-gamma neutron activation analysis (PGNAA) was considered as the company recognised that it would measure through the full conveyed cross section continuously and produce multi-elemental measurements unaffected by particle size, dust, moisture content, layering and segregation, mineralogy and belt speed.GEOSCAN analyses over various analysis periods will be collected to identify variability in the conveyed material quality and used to generate tonnage-grade curves so that an optimal diversion (bulk sorting) tonnage increment can be determined. Measurement increment time can be customised to suit site requirements. CITATION:Kurth, H and Balzan, L, 2017. Assessing bulk sorting suitability at the New Afton mine, in Proceedings MetPlant 2017, pp 315–323 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017

By J Carter, B J. Armstrong

Best practice for the submission of samples to an internal or commercial laboratory requires quality control materials to be included for the purpose of independently and comprehensively assessing laboratory performance. These quality controls include the use of certified reference materials (CRMs) and may be blind to the laboratory. Iron ore companies purchase these materials from reputable manufacturers from stock of run-of-mine materials at the appropriate grades. The international standard, ISO 17034 (ISO, 2016), specifies the competency requirements for organisations manufacturing reference materials, and includes rigorous requirements for the assessment of homogeneity, stability and establishment of property values and their uncertainties. Homogeneity is one of the most important measures of suitability for all certified reference materials and refers to the degree to which the composition and properties of a sample are uniform throughout the batch, relative to the analytical precision of the method. More specifically, homogeneity studies of candidate reference materials should be assessed for both within sample variance and between sample variance with appropriate statistical controls. The design and application of homogeneity studies are discussed as they apply to both crushed and pulverised reference materials. Crushed certified reference materials have been utilised by the iron ore industry for a number of years and provide the user with a critical assessment of variances in sample preparation in addition to analysis. Crushed reference materials are similar in presentation to an RC sample and are generally used as discrete parcels of material submitted to the laboratory from the field. Pulverise certified reference materials miss the sample preparation step and are subsampled from th delivered sachet at the point of analysis. This paper compares the relative homogeneity performance of crushed and pulverised certified reference materials by grade across key iron ore chemical constituents. Outcomes are benchmarked to the international standard ISO 9516 (ISO, 2003) for the determination of various elements in iron ores by lithium borate fusion and X-ray fluorescence. Practical implications are discussed with reference to a case study from an iron ore laboratory in the Pilbara.

Sep 18, 2023

By G B. Smith

Barrick (Australia Pacific) Limited initiated a trial of Caterpillar’s Minegem autonomous loader technology in 2009 at the Kanowna Belle mine in Kalgoorlie. Autonomous loader technology offers the potential to improve loader productivity, reduce operating costs and improve safety through removing personnel from the mine operating environment. This paper discusses the implementation of the technology at the mine site, the data collected during the trial and quantifies the benefits of using automated loader technology in comparison with teleremote loader operation. The lessons learned from the trial and work planned for the future in respect of this technology is also discussed.

Mar 21, 2011

By K C. Runge, E Tabosa, A Jankovic

Flotation recovery in geometallurgical modelling is usually predicted based on relationships developed from batch flotation testing of different ore types. These batch flotation tests are usually performed at a constant set of operating conditions and at a fixed feed grind size P80. Usually the laboratory feed grind P80 is that which is expected to be produced in the full-scale flotation circuit for that particular ore type.Flotation recovery will be a strong function of the valuable mineral particle size distribution, with lower recovery of ultra-fines due to poor flotation kinetics, optimum recovery for the intermediate sized particles and lower recovery for the coarser particles due to poorer liberation of this fraction. This valuable mineral particle size distribution is not characterised by the solids P80 parameter alone. The proportion of material in each class will also be a function of the slope of the size distribution and the degree of preferential grinding of the valuable mineral in comparison to the total mass of the ore.This paper will demonstrate (through example) how these other size distribution parameters can change with a change in grinding technology, the size and operating conditions used in a grinding unit and the characteristics of the classification technology used in conjunction with the grinding unit. Case studies will be presented that demonstrate how this can result in these parameters being very different in laboratory testing to that produced in the full-scale comminution circuit. A rule of thumb that laboratory rod milling rather than ball milling produces a size distribution most similar to that of the full-scale grinding circuit will be challenged. These differences can result in a significant change in flotation recovery. It is therefore important to consider these parameters when developing a laboratory geometallurgical program, to enable more accurate prediction of the flotation recoveries that will be achieved in the full-scale process.CITATION:Runge, K C, Tabosa, E and Jankovic, A, 2013. Particle size distribution effects that should be considered when performing flotation geometallurgical testing, in Proceedings The Second AusIMM International Geometallurgy Conference (GeoMet) 2013 , pp 335-344 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 29, 2013

By H Ishikawa, R Halomoan, S Palaniandy

The Karara iron ore project is a magnetite operation consist of open pit mining and concentrator to produce high-grade magnetite concentrate. The concentrator has adopted three stages of comminution, ie fine crushing in the high pressure grinding rolls (HPGR), primary ball milling and fine grinding in the TowerMill plus magnetic separation in between these comminution devices. Since 2014, the concentrator has increased the plant feed rate by 18 per cent. Meanwhile, the ore hardness has increased by 13 per cent to a Bond work index value of 15 kWh/t that led to a coarser flotation feed. Karara Mine has decided to shift the comminution workload from the primary ball mill to the TowerMill circuit by bypassing the 100 µm fine screen in between the ball mill and TowerMill circuits. This action has increased the circuit feed particle size distribution with a top size close to 1 mm. The specific energy consumption of the TowerMill circuit was approximately 3.4 kWh/t, and the circuit product sizes (P80) were ranged between 38 and 45 µm. A joint process improvement exercise was carried out to reduce the circuit product size closer to the magnetite liberation size, ie 35 µm. Among the activities were circuit audit, recommendation for improvement, modelling and simulation, multicomponent analysis, implementation of recommendations and quantification of the improvement. One of the key findings was the density effect of multicomponent minerals in the hydrocyclone. The analysis revealed that the low density coarser gangue minerals were bypassed to the hydrocyclone overflow stream that has resulted in a coarser particle size distribution. Meanwhile, more than 20 per cent of fine (-35 µm) high-density magnetite particles were recycled back to the mill through the hydrocyclone underflow stream and increased the circulating load. Based on these outcomes, several recommendations such as conversion to bottom feed configuration, use of smaller grinding media, high operating hydrocyclone pressure and additional grinding power to the TowerMill circuit were made to improve the overall circuit performances. Karara Mine has prioritised to implement those recommendations that have a minimal financial implication. Full-scale plant trials with bottom feed configuration and 17 mm grinding media were conducted to evaluate its performances. These trials have indicated that the grinding efficiency in the TowerMill was enhanced by 10 – 30 per cent. In May 2017, all the five TowerMills were converted to the bottom feed configuration. This paper discusses the impact of shifting the comminution workload load from the primary ball mills to TowerMill circuit and the performances enhancement of the TowerMill circuit. CITATION:Palaniandy, S, Halomoan, R and Ishikawa, H, 2018. Shifting the comminution workload from the primary ball mill to TowerMill circuit, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 163–176 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

This paper puts the view that, for one gold deposit in Victoria at least, the Australasian Code for the Reporting of Identified Mineral Resources is severely deficient. The author questions whether or not the Code constrains the proper dissemination of information relevant to resource valuation. The author offers a view about the estimation of inferred resources, and provides data believed pertinent to the proper valuation of Ballarat Goldfields Ltd Ballarat East Project.

Jan 1, 1990