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By J D. Grobler

In the heavy minerals industry wet high intensity magnetic separators (WHIMS) are widely applied for primary magnetic separation of magnetic minerals and non-magnetic minerals. This piece of equipment is well known for its robustness to handle a wide range of feed conditions and still produce stable product qualities and yields. A heavy mineral production plant aimed to increase production through their WHIMS plant containing 11 duties and 26 units. Instead of adding new units an alternative approach was followed to firstly maximise the efficiency of the current circuit and secondly to consider possible reconfiguration of the circuit to produce additional product tons for minimal capital investment. In order to characterise the current circuit’s efficiency, identify pockets of excellence and determine the areas for improvement the whole circuit was surveyed several times and mineral mass balances were drawn up.This paper aims to: discuss the modelling process of the WHIMS circuit,explain the calibration and validation process followed to ensure the accuracy, anddemonstrate the sensitivity analysis performed on the different options. From this analysis an efficiency criteria was developed to compare different circuit configurations that enabled the production plant personnel to make an informed decision on the way forward.

Oct 5, 2011

Bolivia, due to its turbulent past with a history of constant military coups, has given an image of complete instability to the foreign investor. The effects of this have been several fold, the major one resulting in a complete lack of exploration in modern terms since their revolution in 1952. What was overlooked by the foreign investor was the fact that revolution produced Agrarian Reform which is the foundation of the stability which Bolivia enjoys today. Another factor that is overlooked is the fact that its past history is one of vast mining fortunes having being made. Their political problems resulted in economic chaos in 1985 with an annual inflation rate of 26,000 percent. This resulted in the collapse of the government but the democratic process continued. Then came the so-called"South American Miracle" in 1986 when the government of Dr. Paz Estenssoro enacted an extremely harsh austerity program which consisted of the abolition of wage and price controls, the abolition of monopolies, the right to hire and fire, the weekly auctions of dollars and the free convertibility of currency which yielded a stable government with 8 percent inflation. This was followed by massive personnel reductions in the various mines and other industries.

Jan 1, 1991

By B P. Wrench, N R. Steward, C Wu

A gold mine in southern China has transitioned from an open pit operation to a fully underground mine. An overhand mining method is used which requires the mined stopes to be filled with backfill having an unconfined compressive strength of at least 0.35MPa. Tailings from the process plant is deposited into separate flotation and Carbon in Leach (CIL) tailings storage facilities. The tailings has a high fines content and the thickener on site could only produce a dilute flotation tailings at a solids content of about 30 wt%. This resulted in two undesirable outcomes: the density of flotation tailings in the Tailings Storage Facility (TSF) was significantly lower than planned so that the TSF could not store the life of mine tailings and that the backfill product had to include a high percentage of manufactured aggregate and increased cement content to achieve the required strength. This paper presents results of a tailings study which identified that the flotation TSF would be capable of storing the remaining life of mine tailings if an amended backfill product made up of 100% of flotation tailings could be introduced. A 100% tailings backfill with the addition of 8% cement was developed by classifying the tailings and using the coarser fraction in the backfill. This backfill allowed 60% of the flotation tailings to be placed underground and only the remaining 40% in the flotation TSF. A new thickener was designed and installed to thicken the tailings and rheological testing of the tailings, using a closed loop pilot plant, provided parameters to upgrade the underground reticulation system to deliver cemented backfill to stopes throughout the mine and to deliver thickened tailings to the TSF. The revised design was implemented and has resulted in considerable cost savings. CITATION:Steward, N R, Wrench, B P and Wu, C, 2018. Optimisation of surface tailings storage and tailings backfill – a case study, in Proceedings Mine Waste and Tailings Stewardship Conference 2018, pp 454–464 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 23, 2018

By T Baumgartl, D Mulligan, R Haymont

Mining at the Mt Leyshon Gold Mine in semi-arid north Queensland stopped in 2002. Newmont Australia has recently initiated a thorough post-closure water management study of the site by revisiting the existing information and conducting new water-related investigations. The focus of this paper, which is the first publication on post-closure environmental management of the site, is an overview of the site water quality in view of the sources and spatial distribution of polluted mine water, and also the performance of cover systems in controlling water flux though mine wastes. Since the mine closed the rehabilitation of waste rock dumps and tailings dams have significantly improved water quality in the surface receiving waters. However, the Scats Stockpile, the Heap Leach and Old Plant areas, which can potentially produce acidic waters, enriched with heavy metals and arsenic, are the top management priority. Modelling of the potential transport of contaminants in groundwater needs further investigations. A detailed examination of the waters in seepage sumps showed high concentrations of manganese, cobalt, nickel and selenium, which were previously overlooked. The study also showed distinctive chemical signatures for waters at different locations: the waters draining from scats, supergene materials and waste rocks have distinctly lower pH and higher concentrations of dissolved iron, sulfate, heavy metals, Mg, Mn, U, Se and As. While, the tailings sumps are more alkaline, and are enriched in Na and Cl. The southern tailing sump is characteristically As rich. The waters draining from the supergene materials have higher Cu concentrations. Assessment of the cover monitoring systems showed that although covers pass the design criteria, automated recording of data may ignore any failure of the monitoring system. Recalibration of the moisture sensors not only showed realistic moisture values compared to rainfall data but also showed that the permanently installed system records values that are higher than those of the mobile system. Event-driven recording of data overlooks infiltration events. Besides, with a higher time resolution (daily measurements) the breakthroughs could be clearly detected. Modelling of the water balance in covers is underway and an example is given here. Newmont is currently reviewing water management options and is willing to share the lessons learned.

Jan 1, 2006

By R L. Brathwaite

The mesothermal quartz-scheelite lodes of the Wakamarina valley are one of twelve known mined or prospected gold-bearing areas in the Marlborough Schist. Recorded production was 556 kg gold, a little silver, and c. 390 t scheelite. 134 m of the 1800 m long Golden Bar reef are accessible in the No 2 level of the Golden Bar mine. The reef is a typical multi-banded mesothermal vein, mostly c. 1.75 m wide, enclosing narrow horses of schist country rock. Scheelite is sparsely distributed, and is more common in small veinlets in the hanging wall schist. The country rocks are textural zone I-1m schists of prehnite-pumpellyite to pumpellyite-actinolite metamorphic facies. Their geochemistry suggests they are part of the Caples Terrane, and of calc-alkaline volcanogenic arc origin. The associated Wakamarina Quartzite is strongly recumbent folded, and of the same metamorphic grade, with abundant pumpellyite, stilpnomelane, and garnet, presumably spessartine. Although it has geochemical signatures of a deep sea sediment, it is depleted in Cr and Cu, and greatly enhanced in K and Ti, when compared with a standard chert. It also has trace element characteristics of a calc-alkaline arc-related sediment. However, associated greenschist has MORB-like incompatible element chemistry. The Golden Bar reef lies within a steeply dipping, normal to transtensional dip-slip fault adjacent to a shallow-dipping mylonite shear zone, which, at least on the footwall side, is 040 m wide. The shear foliation has been severely dragged down to nearly parallel the Golden Bar reef within 1 m of the quartz lode. Preliminary structural analysis suggests that the shear zone is extensional. X-ray diffraction analyses of the wall rocks show a progressive depletion of amphibole, stilpnomelane, and pumpellyite towards the reef, and enhanced illite/muscovite and Kfeldspar adjacent to the lode, along with possible graphitic carbon within 10m. Two zones of intense quartz veining occur, one adjacent to the hanging wall for 12 m and one from 40 m outwards. Quartz vein systems in the country rock are complex and span from pre-schistosity to post-mylonite. They include multiple generations of quartz, actinolite, stilpnomelane, pumpellyite, albite, adularia, chlorites, illite/muscovite, calcite, and scheelite. Metal analyses across the Golden Bar reef showed gold values of 0.13.1 ppm, and low tungsten values, consistent with the observed sporadic scheelite occurrences. As and Sb are at background levels, but enhanced Cr (150 - 430 ppm) relative to the schists (30 - 41 ppm) suggests that the source hydrothermal fluids passed through and leached mafic to ultramafic rocks.

Jan 1, 1994

By N Rivera, A Music, C Cisternas

In an underground mine operated with panel caving and subjected to high stresses, geotechnical events such as collapses or rock bursts are fairly recurrent. Both situations can involve risks for people, considerable production losses and increasing operational costs.This paper discusses an operational methodology for the recovery of the undercutting front carried out at El Teniente mine, which uses panel cave mining with post-undercutting, after the occurrence of severe damage due to a seismic cluster. The main objective of the recovery of the undercutting front is to prevent the spread of the collapse to the production level, risking the operational continuity. The methodology is the result of repairs that were carried out in the year 2014 at the North Reserves sector from El Teniente mine. Its characteristics are an undercutting front of almost 1000 m long, with the presence of relevant structures and faults, high stresses and high seismic activity.The practical implementation of the proposed methodology was successful since it prevented the spread of the damage, completely recovered the undercutting front and avoided production losses during the execution of the repairs. Also, considering the origin of the damage and the operations associated to the subsequent recovery of the undercutting front, in this paper we discuss the main control variables to be measured. These variables should allow any operator and short-term planner to take action in mines operated with conventional panel caving in a complex geotechnical environment.CITATION:Rivera, N, Music, A and Cisternas, C, 2016. Recovery of the undercutting front in a mine with conventional panel caving – case study at North Reserves sector, El Teniente Mine, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 713–722 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

THE paper is principally eoncerncd with experimental work carried out the author whilst a number of the metallurgical staff at the Cockle Creek works. The metallurgical has been discussed sufficiently for the reader to follow the course of the experiments but the actual plant has only been described in so far as it effected metallurgical treatment, since the arrangement of such a smelter is a matter of common knowledge.The lead-roasting plant consisted of Godfrey roaster, Dwight-Lloyd maehines and Huntingdon-Heberlein pots. The usual treatment was in the Godfrey furnaces, followed by sintering in the Huntingdon- Heberlein pots. The paper is divided into two parts in the Godfrey furnaces and Huntingdon-Heberlein pots. An account of experiments on the utilization of the hood gases from the Huntingdon-Heberlein pots for acid making...

Jan 1, 1924

By G Clarke

Commissioning of the Cannington processing plant began in October 1997. The nameplate capacity (of 1.55 million tonnes of ore per annum) was achieved relatively quickly. Since then (like many mines) the operation has strived to increase throughput and improve valuable metal recoveries, to offset declining head grades and lift the value of the operation. The processing plant now has the capability of treating over 3.2 million tonnes of ore per annum and in financial year 2005/06 the combined concentrate production exceeded 600 000 wet tonnes, approximately 80 per cent above concentrate output in the first full year of operation (at the design feed rate). This improved performance was achieved by making changes and additions to each of the major unit processes û primary grinding, flotation, leaching, filtering and paste fill preparation. The changes have included: adding a fines flotation circuit, expanding the grinding circuit, adding a pebble crusher, switching from continuous to batch leaching, building paste conveyors and decommissioning the column flotation cleaning circuits. This paper reviews these changes, outlines the current operating practices and discusses the challenges or opportunities that remain.

Jan 1, 2007

By E Kabwe, M Karakus

Deep hard rock underground mines tend to experience high stress as such drives exhibit dynamic responses attributed to a rock burst variant (strainburst). This dynamic behaviour is difficult to predict, and every effort is made to devise the appropriate dynamic support system for its associated failure restraint. This paper outlines the back analysis and the support scheme design for an underground decline that exhibited damage from a dynamic strainburst occurrence. It employs a decline section that experienced a dynamically loaded strainburst that initiated rock fragment ejections. The procedure involves a preliminary structural analysis, a seismic intensity measure, and a rock mass simulation to determine the static stress concentration and ground support system response. The numerical simulation is conducted in FLAC3D which employs the advanced strain-softening IMASS constitutive model governed by two Hoek–Brown (HB) bounding yield surfaces. To account for the post-peak brittleness response associated with strainburst the plastic strain multiplier () is adjusted to 0.0 < < 1.0. The back-analysis shows that the occurrence was initiated by a low-intensity seismic wave that superimposed an extra stress component to the initial static stress which triggered rock fragment ejections. Additionally, the appropriate support scheme comprised of Weldmesh, Fibrecrete, static (split set) and yieldable (Kinloc) reinforcements is recommended and implemented. Thereafter, the bolt’s efficiency is evaluated based on the axial force and elongation capacities and then compared with the published bolt performance data. The evaluation results show that the maximum bolt axial force (0.1 per cent) and elongation (0.006 per cent) are below the designed capacity and rupture strain.

Nov 29, 2022

By H F. Yu, S Ueda, J Diao, W F. Gu, Y Sasaki, H Qin

The main reason for the underutilisation of steelmaking slags is their instability, which is influenced by their complex phase structure. Recycling and sustainable steelmaking slag face challenges due to the presence of magnesium oxide (MgO), a crucial component in steelmaking slag. This study investigates the phase evolution of steelmaking slag during the cooling process with different MgO contents, using high-temperature experiments and FactSage™ software, ver 8.1, (by Thermfact/CRCT and GTT-Technologies) thermodynamic equilibrium calculations. X-ray diffraction (XRD) and scanning electron microscope - energy dispersive x-ray spectroscopy (SEM-EDS) analyses identified main phases in steelmaking slag, including Ca2SiO4 (C2S), RO (MgO-FeO solid solution), Ca2Fe2O5 (C2F), and Ca3SiO5 (C3S). The study reveals that RO phase increases as the MgO content increases. C3S precipitates from steelmaking slag with a 12 mass per cent MgO content at a reduced temperature of 1400°C. It is important to note that C3S remains in the steelmaking slag even after slow cooling. This may be due to the substitution of Ca2+ in C3S by Fe2+ and Mg2+ ions. Intriguingly, the precipitation of f-CaO in steelmaking slag with 10 mass per cent of MgO content occurred after one year, while there was no manifestation of f-CaO precipitation in the steelmaking slag with 12 mass per cent of MgO content even after one year. This discrepancy suggests a potential stabilising effect of an appropriate amount of MgO in steelmaking slag. However, it is crucial to emphasise that this inference lacks supporting data, necessitating further research to validate this hypothesis. The significance of this work is in uncovering the complexities of steelmaking slag behaviour, providing essential insights for optimising recycling processes. The research sheds light on the factors that influence the phase composition and stability of steelmaking slag, contributing to the utilisation of steelmaking slags, promoting environmental sustainability, and enhancing the overall efficiency of metallurgical processes in the current industrial landscape.

Jun 19, 2024

By J Herd, J Rowe, M Cutbush, d F. Aziz

WearApp provides expertise for assessing the degradation of removable screening media panels on vibrating screens right in a user’s pocket. Through the WearApp application, users can simply take a picture of a panel using their mobile, enter some basic information and have the application assess the wear to provide a recommendation for whether the panel needs to be replaced. Where traditional mechanisms for assessing panel wear only measure a few points across the panel face and rely on having personnel with specialised knowledge available to perform the assessment, WearApp uses deep learning models to analyse the entire panel face and support the user to make an informed decision. The application works through analysing a panel image and using a model to automatically detect the corners of the panel. Given the known dimensions of the panel, this enables the application to calibrate the pixel size against a known reference. A second set of models then detect the apertures and measure their dimensions. With the aperture dimensions defined the application assesses the wear of the panel through referencing a stored 3D model of the aperture. Finally, the data from each aperture is collated and the wear of the entire panel face defined. Since WearApp performs measurement of the entire panel face, it also allows the user to perform a more detailed analysis of the panel’s wear profile. Where typically, the panel wear is only measured in a few locations, WearApp’s analysis enables users to visualise the panel wear across the entire panel face, identifying areas of high wear that could be leading to premature panel replacement. Additionally, because the entire panel face is measured the change in screening efficiency can be calculated accurately for the worn panel, even taking into account the impact of aperture pegging by small rocks.

Sep 1, 2024

By A G. Sheard

Fire safety requirements inside tunnels have become more demanding as tunnel designers consider the impact of potentially larger fires. Tunnel ventilation equipment is required to clear hot gases in the event of a fire. This is vital to maintain smoke free escape routes for people trapped in the tunnel and to facilitate safe access for emergency services. As the fire becomes larger, the temperature of clearing hot gases increases. Traditionally, engineers have taken into consideration gas temperatures of 250°C when designing tunnels. Because of larger fires, engineers must now design equipment to clear hot gas up to 400°C.Increasing the temperature of hot gases to 400°C requires tunnel ventilation equipment that goes beyond historic limits. As temperature rises, material strength reduces, consequently mechanically constraining fan aerodynamic performance. Developing tunnel ventilation equipment suitable for clearing hot gases at 400°C requires a fan technology that is more typical of industrial turbomachinery. The standards EN 12101-3:2002 and ISO 21927-3:2006 defi ne the necessary design criteria and testing methodologies to verify that a range of tunnel ventilation equipment is capable of extracting hot gases.This paper describes the process by which the authors certified in accordance with EN 12101-3 and International Organization for Standardization (ISO) 21927-3 a range of powered ventilators suitable for clearing smoke and hot gases at 400°C for two hours. Proving the high temperature capability of the new range provided a challenge as a consequence of the large physical sizes and high motor powers involved. Additionally, the need to install vertically, as well as horizontally, imposed high thrust loads on motor bearings, further complicating both mechanical design and testing. The paper presents the methods by which the authors overcame these challenges.

Mar 8, 2011

By D Kepert

It is the role of the exploration geologist to create wealth through the discovery, delineation and characterisation of economic mineralisation. This requires a critical depth of geological understanding.Unfortunately, the resource industry is well known for its cyclic nature. Many of the current generation of workers have only ever experienced the boom of the ‘super-cycle’ and are only just discovering the negative side to the business. For the case of the geologist and especially the exploration geologist, the magnitude of peaks and troughs are usually amplified and may become destructive to all parties. During the uptime a healthy stream of exploration good news becomes the staple diet of company releases, in particular those of junior companies attempting to bolster the share price. The geological knowledge and experience gained thus forms a significant and integral part of the value and therefore, future of a company. On the downturn it is often viewed that geologists are a luxury, an optional extra and a burden on the bottom line with companies entering a period of memory loss and myopia.Retention of geological knowledge however remains critical as projects, companies and cycles mature. Beyond exploration per se, this knowledge becomes both fundamental in de-risking and commercialising an asset (through development or divestment) and in positioning the company for cyclic or counter-cyclic opportunities.The growth and retention of this knowledge base is difficult to quantify in terms of direct value but becomes one of a successful resource companies greatest assets. At worst, its loss can lead to millions of investors’ funds wasted on missed opportunities, drilling, or poorly designed plant and mine.But the rocks are around for the longer haul and pay little notice to the vagaries of the scurrying of Man.This paper reflects on some of the authors own observations through 25 years of iron ore exploration, in why it is critical to always rigorously question the prevailing geological (mis)understanding and the technical and commercial benefits which that may bring, and looks forward to the future.CITATION:Kepert, D, 2015. Geology – the affirmative case, in Proceedings Iron Ore 2015, pp 285–298 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By A Scott, I Onederra

A great deal of technical and research effort has been applied to the development of models to predict fragmentation from rock blasting. A number of quite useful empirical or engineering models are currently available to blasting engineers and consultants, while more sophisticated approaches using mechanistic and numerical descriptions of rock breakage continue to be developed and applied by researchers and explosives companies.The fragmentation resulting from any blast will be heavily dependent on the properties of the rock mass being blasted; however, most empirical models rely on ‘rock factors’ generated from simple rock mass properties to describe the influence of the rock on the blasting outcome. In contrast, mechanistic models need explicit rock mass properties that require sophisticated laboratory measurements and detailed structural data if realistic outcomes are to be generated. The fragmentation modeller is caught between excessively simple rock mass descriptions for the empirical models and excessively complex data requirements for the mechanistic models.This paper briefly reviews the basis of a range of fragmentation models and the rock mass properties on which they rely. Shortcomings in the way that the mining industry tends to characterise the blasting properties of rock are discussed and some practical approaches are described to quantify these properties in both operating and greenfield mining environments. Case studies are presented where specific additional breakage properties and modelling features have been needed to generate a useful description of the fragmentation achieved.CITATION:Scott, A and Onederra, I, 2015. Characterising rock mass properties for fragmentation modelling, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 149–160 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

This paper presents an overview of a program PC-BC developed for application to the design and evaluation of block cave operations. Conventional mine planning software tools are not well suited to the evaluation of this type of deposit. The paper looks at the modelling approach as applied to a block cave mining project. The following steps are described:Initial preparation of data including block models, draw point footprint geometry and draw cone geometry. Computation of individual draw point reserves. Procedure for modelling of vertical mixing of material within each draw point and subsequent determination of the best height of draw for each draw point based upon an economic cut-off value. Smoothing of draw heights amongst neighbouring draw points to produce a realistic draw envelope. Mineable reserves within the envelope are then computed. Tools for preparation and evaluation of various production schedules. This includes definition of draw rates, and rates for commissioning new draw points. In an operating mine, the capture and analysis of daily draw tonnages is important. How PC-BC accommodates this is described as well as the processes for depleting the draw column reserves. In the 12 years since the program was first developed, it has been used on a number of projects for feasibility studies and operating mines. Some practical examples of the use of the program in these projects are presented. Finally, some commentary on the sensitivity of various parameters is presented. Particular emphasis is placed on the overall footprint design.

Jan 1, 2000

By C Mark, Z Agioutantis

This paper presents an empirical design methodology that is based on successful US roof support systems using both primary and secondary support in coal mining entries and intersections. The recent nationwide dramatic reduction of roof fall rates, especially in areas with weaker roof, can be directly correlated to the effectiveness of the roof support systems. A large database of roof fall histories at several mines is used to define the approximate boundaries of three modes of roof support with respect to roof strength as classified by the Coal Mine Roof Rating (CMRR) and in situ vertical stress as indicated by the depth of cover. These roof support classifications are: • Suspension, where roof bolts mainly provide skin control for strong roof. • Beam building or reinforcement, where a roof of moderate strength can be supported by roof bolts only. • Supplemental (secondary) support, where the primary support by roof bolts may be augmented by several secondary support systems, eg cable bolts, trusses, additional roof bolts or standing supports. The Primary Support Rating index (PSUP) captures the capacity of the primary roof bolt system as a function of the actually implemented roof control plan, ie roof bolt length, roof bolt density, and roof bolt capacity, while it does not consider the type of bolt. The actual PSUP value is compared against a suggested PSUP value derived from statistical analysis of US case histories. Where secondary support is indicated, the expected rock load determines the necessary capacity of the secondary support system. A new (free) software package, Analysis of Mine Roof Support (AMRS), implements the design methodology and also allows comparison with other international indices such as the Reinforcement Density Index (RDI), the PRSUP, etc.

Nov 29, 2022

By A Weston

Northparkes Mines is a joint venture between Rio Tinto and the Sumitomo group and is operated by Rio Tinto to produce copper concentrate from ore sourced from open cut and underground. Underground ore is mined with an owner operator workforce using the block cave method from the E26 deposit, with the first lift of the cave now completed. Development of the Lift 2 block cave commenced in March 2001 using a contract workforce. The Lift 2 Project required the mining of 14 700 m of decline and lateral development to establish a new mining horizon at the 9450 level and to develop two new conveyor declines. Also included in the scope was the excavation of a Crusher chamber to house the jaw-gyratory crusher. This paper describes the excavation of the hydroset chamber and orepass that sit immediately underneath the Lift 2 Crusher chamber. It includes risk assessment, planning, development of method statements and standard operating procedures, through to the excavation of the orepass and the installation of ground support in seismically active ground. There was a major ground failure in the backs of the conveyor feeder chamber during its excavation, which affected the excavation of the orepass due to its proximity to the breakthrough site.

Jan 1, 2005

By J-P Franzidis

Mill operators have traditionally been forced to rely on grade-recovery curves and overall flotation rate constants when analysing proposed improvements to plants. This has led to loss in money and time when a proposed change that showed potential in laboratory scale tests failed to show improvement in the plant. Frequently, this is a result of the operators being unable to gain insight into how and why the proposed change affected the flotation performance. This is due to the classical models not including any description of the subprocesses of flotation and their individual contribution to the overall flotation performance. A new flotation model has been developed as part of the AMIRA P9 project that separates the flotation process into subprocesses and includes the contribution of both the pulp phase and froth phase to the overall flotation recovery. It is not possible to determine the individual components of this new model on traditional pilot plants as they lack the required flexibility and scale. Therefore a new pilot plant has been developed known as the Floatability Characterisation Test Rig (FCTR) that has the flexibility and features required for the determination of the flotation subprocesses. The flexibility and features of the FCTR also make it an ideal tool for investigations into many different aspects of flotation research. These include the effect of reagents, grinding, and power on the flotation performance. This paper will describe the methodology for using the FCTR in these fields of research and highlights the advantages of using the FCTR over traditional methods.

Jan 1, 2000

By R P. Langford, T A. Moore

Indonesia over the last 15 years has experienced a surge in coal exploration, which has led to the development of a major export industry. This coal exploration has improved the understanding of the geology of the Indonesian coal deposits. The main economic coal deposits are of Eocene and Miocene to Pliocene age, which mainly occur in Kalimantan and Sumatra and were formed from peat deposits in an equatorial paleoclimate similar to that prevailing today. Some of these peats were domed peats, which grew above the normal water tables, under a climate of year-round rainfall; these peats grew above the level at which waterborne mineral matter can enter the system, resulting in low ash and sulphur, and locally very thick coal. It is believed that such peats have formed the unusually thick, low ash, and low sulphur Miocene coals of Indonesia. Coal deposits of Eocene age are typically characterised by thinner seams, with relatively higher contents of ash and sulphur. The Miocene coals and Eocene coals both appear to have formed in lacustrine, coastal plain or deltaic depositional environments, similar to the modern peat-forming environments of eastern Sumatra and parts of Kalimantan. The Eocene coals formed mainly in extensional tectonic settings. Miocene - Pliocene coal deposits formed in a range of tectonic settings; the most significant, for large economic coal deposits, are the foreland basin setting of the large Neogene coal deposits of South Sumatra.

Jan 1, 1999

By Sparrow GJ, Woodcock JT

A sample of pyrrhotite flotation concentrate pulp assaying 15.3 g/t An, which had been prepared from an old tailing dump, was treated to extract the gold. Examination of the concentrate with an SEM showed that exposed or free native gold, 5-40 ¦m in diameter, was present but no locked gold was observed. Direct cyanidation of the concentrate to extract the gold showed that the flotation reagents present inhibited gold extraction. A range of pre-treatments was used to overcome these effects.Direct cyanidation for 48 h extracted only 26% of the gold, indicating possible contamination of the gold in the concentrate with flotation reagents. Pre-treatment of the concentrate pulp by aeration for 24 h, or by 72 h aeration with an addition of 3.65 kg/t of sodium sulphite, gave little improvement in gold extraction by subsequent cyanidation. Pre-treatment by filtration, or by aeration with 12.5 L/t 100 volume hydrogen peroxide, followed by cyanidation for 48 h gave gold extractions in the range 67-77%. Combining filtration and an aeration period with hydrogen peroxide addition raised the subsequent cyanidation extraction of gold to 88%, giving a tailing assaying 1.5 g/t Au.

Jan 1, 1990