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By L Snyman, S Webster and J Samosir

Northparkes is located 27 km north of the township of Parkes in central New South Wales, Australia. The operations consist of underground block cave mines and an ore processing plant, which produces high-grade copper and gold concentrate. Production is currently sourced from the E48 Lift 1 block cave mine and open cut stockpiles. Mining commenced at Northparkes in 1994 as an open cut operation. Underground block cave mining began in 1997. Northparkes was the first mine in Australia to use the highly efficient block cave mining method, which relies on gravity and natural rock stresses to fragment and recover the ore.The E48 extraction level is located approximately 581 m below surface and consists of ten extraction drives and 214 drawpoints. Several stress measurements carried out at various levels in both E26 and E48 indicated a low underground regional stress environment and a low to moderate stress state in the E48 orebody. The E48 block used a post undercut strategy that was initiated in 2009, with production commencing in September 2010 and cave-through to the surface occurring approximately four months later in January 2011. Changes to the cut-off grade and fixed prices meant that Northparkes was able to develop an additional two drives to the north of the existing cave and one additional drive to the south. Modelling of the cavability of the additional drives indicated that the cave would not readily propagate to sufficient height of draw to mobilise the ore and tended to arch over to the existing cave shape. Based on modelling and a desire to reduce the risk of the project, preconditioning was adopted. Along with the requirement of safely hydrofracturing an active cave, a measure of the success of the preconditioning was desired. Few block cave operations have developed extension drives adjacent to existing caves.This paper summarises the lessons learnt from the development of this extension project, with a specific focus on ground control and monitoring.CITATION:Snyman, L, Webster, S and Samosir, J, 2016. E48 cave extension at Northparkes, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 111–118 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

Coal mining legislation makes frequent reference to æSafety Management SystemsÆ but there is a chronic shortage of useful guidance material as to how these might be applied to hazardous exposures. Several studies have indicated that for each death that is reported as a result of an industrial æaccidentÆ, there are five deaths that caused by occupational exposures. Because the deaths from occupational exposures do not occur on site and often well after employment has ceased, they are generally unreported. Improved access to mortality data from coroners, the Australian Institute of Health and Welfare and superannuation service providers (early claims from death and total permanent disability), has given rise to some analysis of death and disability data that provides evidence that there are emerging opportunities to develop and improve safety management systems for hazardous occupational exposures. Issues explored include how safety management systems might be developed in relation to dusts and chemicals and other hazardous exposures to ensure the risk of disorders with long latency periods are reliably assessed and the exposures effectively managed. The current standards and guidelines which refer to safety management systems in general or to management of exposure related hazards are examined. Many standards are based on dose-response studies that provide for an acceptable percentage of workers to suffer adverse health outcomes. An alternative management system might be to apply dose-response relations to health surveillance to identify æat riskÆ individuals and effectively manage health and related safety risk at an early stage.

Jan 1, 2005

By A Kondratiev, A E. Moiseev

Viscosity of oxide melts is one of the fundamental physicochemical properties that plays a crucial role in important technological and natural processes like slag flow, slag/metal separation, volcano eruptions etc. However, many oxides melt at extremely high temperatures and are highly corrosive in the liquid state, which makes experimental measurement of melt viscosity by traditional experimental techniques a difficult and expensive, if not unachievable, task. In this case it might be useful to employ other methods of viscosity determination such as modelling or simulation. In the present paper the shear viscosity coefficients of selected pure refractory oxides (CaO, MgO, Al2O3 and others) have been simulated at temperatures above their melting points via the classical molecular dynamics and compared to the available viscosity data (eg experimental viscosities, other model predictions) collected by the authors. The simulation has been carried out using the noncommercial molecular dynamics simulation package LAMMPS and the Born-Mayer-Huggins potential, which parameters for the selected oxides were taken from the literature. Several viscosity calculation techniques (the Stokes-Einstein and Green-Kubo equations, the so called Einstein relations, and the non-equilibrium molecular dynamics methods) have been applied to ensure a more reliable viscosity calculation. It has been demonstrated that the simulated viscosity of the selected melts agrees with the available experimental data. It has also been shown that the simulated viscosity of a number of the oxide melts investigated is close to that calculated by phenomenological viscosity models, which supports viscosity extrapolation from the corresponding binaries and ternaries, if no experimental data is present for unary systems. In general, it has been demonstrated that the molecular dynamics simulation could provide a reasonable estimation of viscosity if no other viscosity data is available.

Jun 19, 2024

By Chander S

Properties of surface films on chalcopyrite and pyrite differ due to variations in the mechanism of oxidation of the two minerals. In the case of chalcopyrite the first step in the oxidation is the release of iron as ferric ions, which hydrolyse depending upon conditions prevalent in solution. The iron oxide/hydroxide layer formed by hydrolysis of ferric ions is quite porous and easily detachable from the surface of chalcopyrite. When the surface oxide layer is detached a sulphur-rich layer is exposed making chalcopyrite hydrophobic. The thickness and properties of the sulphur-rich layer determine its flotation response, both in the absence and presence of collectors. In the case of pyrite, on the other hand, iron is released as ferrous ions which require much higher pHs to hydrolyse. These ions remain adsorbed on the surface of pyrite making the surface hydrophilic. When the iron species are complexed with chelating agents such as ethylene diamine tetra acetic acid, pyrite was hydrophobic. Siderite forms in the presence of carbonate ions, which might be present in several flotation systems. Siderite nucleated on isolated sites at the surface. The presence of such a precipitate is likely to influence the interaction of pyrite with various reagents thereby altering its flotation behavior. To determine the mechanism of oxidation, kinetics of oxidation of chalcopyrite and pyrite was studied using several electrochemical techniques, namely, cyclic voltammetry, polarisation and impedance spectroscopy. Floatability of the minerals was investigated by measurement of contact angles on mineral electrodes and by Halimond tube flotation. Impedance spectroscopy was especially useful for estimating various properties of surface film for both the minerals. Properties such as charge transfer resistance, porosity, and capacitances of the surface films on the two minerals are compared under several conditions of oxidation. These properties were found to be a strong function of the rate and the extent of oxidation.

Jan 1, 1993

Gravity gold recovery has been practiced for thousands of years, making it one of the oldest forms of mineral processing. Gold is 19 times heavier than water although the barren rock is generally only 2.7 times heavier. Any potential gold ore needs to be characterised to assess its amenability to a gravity recoverable gold (GRG) process based on well planned and executed test work. Scale up considerations need to be considered in designing a gravity circuit. The economic impact of a gravity circuit should be justified based on the installed cost and likely benefits. Maximising gravity gold recovery results in a faster cash flow, lower operating cost per ounce and higher overall gold recoveries compared to the several weeks required to recover gold adsorbed onto carbon. The advent of centrifugal concentrators such as the Knelson and Falcon, coupled with intensive leaching of concentrates (ILR), has revolutionised gravity gold circuit designs. Considerations associated with the sizing of the centrifugal machines and the percentage of the circulating load (bleed) that should be processed is discussed in this paper. The trends with gravity circuit layout, engineering, as well as optimum dumping cycles, are important areas which require close consideration. Key aspects of these are presented in this paper. There are a number of circuit configurations to be considered, including the integration of different gravity concentrators. Other gravity process design considerations such as fewer modules, the effect of equipment size and enhancement of process efficiency using preconcentration, together with factors that affect OPEX and CAPEX are addressed. Practical considerations of maintenance, security from theft, minimisation of risk and water balance considerations are discussed using different equipment and circuit configurations. The trend towards using gravity recovery in flotation plants is also reviewed. A number of examples are cited and good design aspects highlighted.

Aug 1, 2010

By J OÆDriscoll, R Butler, L Winter

The iron ore mining district of Labrador West and adjacent Quebec is Canada's largest iron ore producer with almost 50 years of production. The area is currently experiencing a period of renewed activity not seen in decades that includes new mine development, mine expansion and exploration for new iron ore resources. All of the past and present production and exploration programs in the district are centred on the Lower Proterozoic Superior-type iron formations of the Knob Lake Group, located within the Grenville tectonic province of the Canadian Shield. The Knob Lake Group is a continental margin sedimentary sequence which was deformed and subjected to greenschist to upper amphibolite facies metamorphism during the Grenville orogeny. Regional deformation and metamorphism plays a key role in making the iron formation of the Knob Lake Group economic. The distribution of orebodies in the district is controlled by superimposed F1/F2 synclines which causes thickening of the iron formation through repetition. Ore mineralogy consists of specular haematite, magnetite and locally martite with quartz as the major gangue mineral. Regional metamorphism has caused an increase in grain size of the ore minerals making it more amenable to concentrating and pelletising. Altius has been active in Labrador West since 2003 and is now the second largest licence holder in the district with several iron ore exploration projects. The Kamistiatusset project is located in the heart of the region's transportation, power and mining infrastructure. The property has seen limited previous exploration, but covers several significant iron ore prospects. Work by Altius includes a helicopter-borne magnetic survey, ground magnetic and gravity surveys, geological mapping, sampling and 6000 m of diamond core drilling all of which confirm both a favourable geologic setting and ore mineralogy.

Jan 1, 2009

Mining operations in the Obuasi mine of AngloGold Ashanti Limited began in 1897 using mainly gravity concentration and amalgamation to recover the gold from predominantly high-grade quartz ores. The mine is primarily an underground operation, although some surface mining still takes place. Ore is currently processed by two main treatment plants: the Sulfide Treatment Plant (STP) for underground ore and the tailings treatment plant for tailings reclamation operations. STP was commissioned in February 1994 to treat 180 000 t/m of double refractory gold ore and it hosted the then world's largest commercial scale bacterial oxidation plant which uses Gencor's BIOX« technology. Gold is recovered by gravity and flotation, with the regrinding of the sulfide concentrate before bio-oxidation to liberate locked gold in sulfi de minerals. The BIOX« product is leached using the carbon in leach (CIL) process. Gravity gold recovery is a major component of STP operations and its contribution to overall plant recovery is about ten to 13 per cent. Gravity recovery has undergone series of technological upgrading, since the very first circuit which consisted of a Knelson concentrator and a Gemeni shaking table which was incorporated into the milling circuit at the start of the plant. Presently, each of the gravity circuits which consists of Knelson concentrator(s), cyclones and Gekko InLine Reactors (ILR), are located at the Milling and BIOX« circuits. More recently a new gravity recovery facility comprising of four 48 inch Knelson concentrators and cluster of ten inch cyclones have been incorporated at the tail of the flotation circuit. An additional ILR will be commissioned in 2010 to treat the concentrate generated from the new Semi Autogenous Mill #2 (SAG 2) Knelson: concentrator tower under construction. Since the inception of STP, significant gravity recoverable gold has been recovered via Knelson concentrators and the employed circuits have seen a number of modifications and upgrades, motivated by ore mineralogical changes and recovery concerns. The pioneering adoption of the ILR technology in 2001 and 2003 was a critical factor in enhancing the improved recovery benefit of the gravity circuits. Therefore the objective of this paper is to highlight the mine's experience in the gravity recoverable gold process with emphasis on plant modifications and gravity equipment upgrade. Operational challenges and the contribution of gravity gold to overall plant recovery are also discussed.

Aug 1, 2010

By T Kojovic

"The index A*b, determined from the Julius Kruttschnitt Mineral Research Centre (JKMRC) drop weight tester (DWT) results, has become well-known in the mining industry as a reliable measure of ore hardness in impact or crushing, having the inferred units of t/kWh. This index evolved from a long history of comminution studies at the JKMRC, including the development of the now superseded JKTech twin-pendulum, the industry standard JK Drop Weight Tester (JKDWT) and the faster alterative JKMRC rotary breakage tester (JKRBT). A reduced version of the DWT, the semi-autogenous grinding mill comminution test (SMC test®), also provides estimates of the A*b though the testing of only one particle size at five specific energies. Experimental determination of A*b using the above devices/tests requires samples, with sufficient mass, to be sent to designated laboratories, registered to conduct such tests. This protocol is fine for bankable and commercial testing, where material characterisation data is used in conjunction with machine specific data in modelling and simulation, and power based calculations. However, for comparative testing, where results are required at the time of sampling (eg for plant troubleshooting or spot-surveys), or for rapid ranking of geometallurgical samples, these existing tests simply do not provide a timely, viable and cost-effective solution. In order to address this critical void in the realm of comparative testing, a new device has been developed, exploiting a central feature of single particle impact testing – that the A*b can be reliably estimated using one precise low energy test. This device, for which a patent is currently pending, called the HIT (Hardness Index Tester), has been precision engineered to allow users to break narrowly sized fragments at a set specific energy, in a safe and easy manner. The manufacturing materials have been chosen carefully to ensure compatibility with the intended use and portability to any site, whilst minimising cost. The device is supplied with a novel quality assurance / quality control (QA/QC) feature, to ensure that the targeted potential energy is consistently delivered. The product from the HIT breakage test can be quickly sized using a single screen to determine the mass per cent undersize, from which the A*b index is calculated directly at site – eliminating the need to send the raw data off-site for analysis. On presized fragments, a single test using 20 fragments takes less than five minutes to complete, and the results are immediately available. The HIT is currently being tested at a major mining laboratory in the US and the results to date have proved it can deliver on all fronts. This paper describes the new prototype device, which offers users a low cost in-house mechanism for estimating the A*b at any mine site, with potential applications on fragments up to 25 mm from drill core, blast chip rejects or the grinding circuit feed. It also outlines the results of field tests carried out by an objective third party mining group and compares the results with those from current industry standard tests conducted on the same material.Citation:Kojovic, T, 2016. HIT - a Portable Field Device for Rapid Testing at Site, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 9–16 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

Legislation introduced for Queensland and New South Wales Coal mines provides different levels of prescription regarding specification of mine seals û generally in relation to capacity to withstand overpressure. In Queensland, the Coal Mining Safety and Health Regulation (2001), Section 341 (d) places a further onus on the statutory ventilation officer to æensure all ventilation control devices at the mine are properly constructed and maintainedÆ and that the ventilation officer æmust ensure a ventilation control device mentioned in the regulation à and installed at the mine meets the design criteria statedÆ for the ætype of deviceÆ. Based on the experience of the author, it appears that risk management and life cycle approach to seals has not been adopted to the same extent as for other aspects of operations. Further, because of the number of disciplines and personnel involved that may influence various factors affecting seal integrity, the opportunity for oversight or unclear allocation of responsibility is considerable. While suppliers can provide explosion or design rated seals, this should only be a starting point for application of the product in a coal mine. Application is often considered by mine planning staff (taking into consideration mine environment parameters such as water, control of gas, spontaneous combustion risk, etc) in conjunction with the colliery ventilation officer, and then construction completed by contractors under supervision of operational staff. After construction, seals often are managed by operational personnel with input from the ventilation officer. Input of the geotechnical engineer into pillar design, roadway opening size, ground support specification and most stable seal location is also required. The need for a customised design approach for each seal site is proposed in order to take into account the many and variable factors that may influence a site so that improved seal performance reliability and predictability can be developed. A program of quantitative as well as qualitative monitoring of performance and triggers for rectification or maintenance action is required, and would provide support to the aforementioned proposal. Many mines rely on visual/audible inspection and periodic bag sampling as the primary means of assessment. Other significant factors such as seal material properties, rib degradation, convergence, floor heave, effects of water on both structural integrity of the seal as well as the air tightness of the seal do not generally receive the same level of attention. Based on the above observations, the author has compiled a reference checklist in regard to the above matters, including aspects of and approaches to mine and pillar design, geotechnical modelling and data collection, civil engineering design, site evaluation and practical options available.

Jan 1, 2005

No paper available.

Jan 1, 1996

By Green A. D M

The establishment of the Imperial Smelting Furnace at Sulphide Coporation Pty. Limited for the smelting of zinc and lead made it necessary to design and install sintering capacity to produce approximately 500 t.p.d. of zinc-lead sinter. The updraught sintering process installed is a recent development and the plant was designed with adequate flexibility and equipment to enable operating staff to investigate the process and achieve maximum production under optimum operating conditions.Sulphur dioxide gases from the sinter machine are passed to a contact acid plant for the manufacture of sulphuric acid.

Jan 1, 1964

By P D. Munro

On the occasion of the 14th Mill Operators’ Conference and marking 40 years since the first one was held in Mount Isa in 1978, it is fitting to review the history of the Conference and its development over that time.The first 10 Conferences were irregularly held at three to four year intervals, with 9 of these in regional centres of Australasia. It is only since 2012 that the Mill Operators’ Conference has become a regular biennial event, alternating with the MetPlant Conference.The number of people attending the Conference has more than doubled to 470 delegates at the 13th one in 2016. It has outgrown its regional beginnings.Papers presented to the previous Conferences have been analysed according to commodity, country of origin, technology and theme plus the affiliation of the authors to discern any trends that may assist in planning the future events.Suggestions are made as to how the AusIMM might wish to arrange its mineral processing/metallurgical conferences.Recent changes to the structure of the Conference providing a more meaningful experience for the delegates and increasing their interaction and involvement should be vigorously pursued.CITATION:Munro, P D, 2018. Mill Operators’ conferences – a 40-year retrospective and a vision for the future, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 5–14 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By I M. Platten, C J. S Sangster, Y Xie, S C. Dominy

Cononish is a steep, narrow NE-SW trending vein system that was emplaced into late Proterozoic metasediments. It shows brittle style deformation and postdates metamorphism and associated Caledonian foliations. The ore shoots plunge 45¦SW, have a 40 to 80?m intersection with the existing underground development and extend between 40 and 260?m down plunge. Small-scale sulfide-bearing domains within the vein carry the highest gold grades. They collectively define the ore shoots, where one or two and rarely three of the domains are present at an individual site in the vein. Gold occurs as electrum, with minor native gold. Silver occurs additionally as tellurides and native metal. The gold/electrum is fine-grained, generally <100?¦m in size and locally clusters. Visible gold up to 2000?¦m in size is rare. Gold and silver are generally spatially associated with sulfides in quartz. The main sulfide is pyrite, but galena, chalcopyrite and sphalerite occur also. Electrum and gold occur with galena in pyrite-hosted fractures. Gold is also associated with the contacts between galena and pyrite grains. Discontinuity of individual domains, variation in domain thickness and internal heterogeneity results in short scale variation in grade across the structure. Over 16?km of diamond drilling and a 1.2?km exploration adit has provided data to support a Mineral Resource estimate of 169?000?oz Au and 631?000?oz Ag reported in accordance with the 2004 JORC Code.CITATION:Dominy, S C, Platten, I M, Xie, Y and Sangster, C J S, 2013. Gold-silver vein mineralisation at Cononish, Scotland, in Proceedings World Gold 2013 , pp 445-454 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 26, 2013

By N J. Beukes, S T. Netshio, M O. de Kock

The Thabazimbi iron ore deposit comprises a series of stratabound orebodies, on average 18 - 25 m thick that are aligned along the faulted basal contact between the Penge Iron Formation and dolostones of the Malmani Subgroup, Transvaal Supergroup. Field geological relationships and petrographic observations suggest that the formation of high-grade iron ores took place after contact metamorphism related to the intrusion of the Bushveld Complex (2.06 Ga) but before the deposition of red beds of the Waterberg Group at ca 1.9 Ga. Hard, high-grade iron ores are predominantly composed of martite and microplaty hematite. Goethite is restricted to supergene-modified ores close to the Late Cretaceous û Early Cenozoic Old African land surface. At depth, the high-grade hematite ores interfinger with low-grade dolomite-hematite and calcite-hematite ores. Iron oxides (martite, microplaty hematite) present in these low-grade ores are texturally indistinguishable from those in the associated high-grade ores, ie ore formation is genetically associated with carbonate metasomatism. Microthermometric studies of fluid inclusions in sparitic carbonates and rare megaquartz reveal their hydrothermal origin. Two compositionally distinct aqueous fluids of shallow crustal origin are identified, namely a Ca-Na-rich high-salinity brine (26 wt per cent NaClequivalent, TH ~160¦C), and an aqueous Mg-K-bearing fluid of intermediate salinity (8.3 - 12.6 wt per cent NaClequivalent, TH~120 - 150¦C). The results confirm that high-grade hematite orebodies at the Thabazimbi deposit owe their origin to an event of extensive oxidative carbonate metasomatism (calcification), similar to that recognised at other important high-grade iron ore deposits in the world. Hydrothermal ore formation is both structurally and lithologically controlled. Size and quality of the orebodies was improved by Late Mesozoic-Cenozoic deep lateritic weathering as carbonate-hematite ores were enriched to friable high-grade ores, but this supergene modification is second in importance compared to the primary event of hydrothermal ore formation.

Jan 1, 2005

By W P. Darcey

Jabiru Metals completed a feasibility study on the Jaguar Base Metal Project in July 2005. The study was based on conventional truck haulage via a decline. Conveyor haulage was considered but not in sufficient detail to provide a meaningful comparison. The current study investigates the cost and productivity of alternative ore transport systems for the Jaguar project. The options considered are conventional underground truck, conveyor, road train, rigid frame truck, monorail haulage and shaft hoisting. Shaft hoisting was not considered in detail due to the high capital outlay for such a relatively short mine life of less than six years. This study goes beyond the common approach of evaluating haulage systems in isolation; it includes development costs, timing of ore production and costs associated with mine services as well as administration and milling costs. The results of this study indicate that the best haulage option for the Jaguar project is conventional truck using the Hitachi AH400 trucks. The net present value (NPV) for this option is A$8.13 million higher than the next best option namely the Kiruna E635 electric truck. The conveyor option has the lowest operating cost per tonne of ore but the longer development time negatively impacts on its NPV. The monorail option is considered impractical due to the number and length of trains required to achieve production targets.

Mar 21, 2011

By P Ottenio, B CarrT

In the last 40 years, the froth flotation process widely spread in the paper industry becoming the dominant technology for ink removal from recovered paper slurries and cellulose fibres recovery. Most of current models used to describe the flotation deinking process are based on hydrodynamic and statistical theories of ink particles collision/attachment to air bubbles. The complexity of these theoretical models, together with the variability of the recovered papers composition, does not allow to define a set of æeasy to handleÆ equations to be used for modelling industrial flotation cells. This main limiting aspect makes that, in several deinking process modelling tools, basic parameters used to characterise the flotation unit, ie yield, ink removal efficiency, water loss, are constant parameters. Although in some process simulation tools the flotation yield/efficiency is adapted to process control parameters (air ratio, pulp flow, pulp consistency), physicochemical variables (namely the pulp frothing aptitude, the pulp surface tension and the ink adhesion energy to air bubbles) are not taken into account to adjust the flotation yield/efficiency. Data collected during recent laboratory and pilot plant experiments focusing on the role of surface active substances on the flotation efficiency were therefore interpreted and used to identify general trends that could be described with simple semi-empirical models. A set of model equations using surface tension and froth removal height as main variables was then defined in order to describe the behaviour of a pilot flotation cell. Trends obtained during the dynamic simulation of the deinking pilot plant were in good agreement with experimental data obtained under similar experimental conditions, thus indicating that developed equations can forecast with good approximation the behaviour of a flotation deinking unit.

Jan 1, 2005

By P K. Singh

Recent advancements in understanding the detonation process are noteworthy, but they are still based on somewhat hypothetical situations. The actual variables that are essential parts of normal blasting practice have not yet been taken into account in such treatments. These include the various initiation practices employed to detonate a column of explosive, from single point initiation to multi-point initiation in blast holes, and the effect on detonation characteristics of both detonators and explosives under multi-deck and multi-hole blasting conditions. The in-the-hole velocity of detonation (VOD) of an industrial explosive is dependent on explosive’s charge diameter and blasthole diameter. The relationship between blasthole diameter and VOD provides a fundamental guideline to the rate of energy conversion and energy release within the detonation front on the interaction of explosives with the confining medium.The in-the-hole VOD of explosives was measured at four experimental sites in India for different blasthole diameters, ie 150 mm to 311 mm, but for identical explosive composition being same particle size, density, viscosity and loaded into blastholes with the same degree of confinement. The results of the studies demonstrated that there is definite relationship in in-the-hole VOD of the explosive and the diameter of the blast hole. The study also confirmed that the explosives initiated with concentrated boosters yielded higher VOD in comparison to those explosives that were initiated with multi-point priming. The measured increase in VOD of explosives for increasing diameter of holes was up to 24 per cent. The rate of change in in-the-hole VOD of explosives increases with increasing blasthole diameter. It can be further stated that the in-the-hole VOD of the explosive reaches a fairly constant value after reaching a limiting/threshold diameter of 311 mm.

Nov 8, 2011

By L Thorburn

In 2009, the Queensland Government developed a series of amendments to environmental authorities (EAs) for mines throughout the Fitzroy Basin in response to studies that assessed the cumulative impacts of mine water discharges in the basin. One of the key amendments was the requirement for all mines in the Fitzroy Basin to develop and implement a receiving environment monitoring program (REMP). The intent of the REMPs was to provide baseline information on the condition of the receiving environments of the mines and any impacts resulting from release of mine-affected water. Since this time, the requirement to complete a REMP has been incorporated into new or revised EAs for mines (including metalliferous mines) in other regions, as well as for other industries that discharge to natural watercourses (such as coal seam gas). This paper discusses the approaches that can be used to incorporate biological monitoring and direct toxicity assessments into REMPs. It highlights the importance of collecting biological data using sound experimental design principles to investigate whether releases resulted in environmental harm; and the use of monitoring data, coupled with direct toxicity assessments, for setting more realistic, site-specific trigger values and release limits (compared to the default guidelines such as Australian and New Zealand Environment and Conservation Council (ANZECC), which may not be appropriate to the region). Implementation of a robust REMP can maximise outcomes for both the proponents and the environment.CITATION:Thorburn, L, 2013. Receiving environment monitoring programs - making the most out of biological indicators and direct toxicity assessments for monitoring of aquatic ecosystems, in Proceedings Water in Mining 2013 , pp 143-148 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 26, 2013

By B Lavin, R Sanford

This paper examines the application of Lean Manufacturing in a mining environment, based on experience within the Rio Tinto entities: Rio Tinto Aluminium, Northparkes Mines and Hunter Valley Operations. The three applications have tested the flexibility of the Lean methodology. Within Rio Tinto, Rio Tinto Aluminium was the first group to introduce Lean. The rollout began in late 2004. It was introduced firstly at Boyne Smelters, Gladstone, as a model site with the initial application in the Carbon Bake Furnace area. It was later extended to other sites including the Weipa Bauxite Mine. LeanÆs successful application within Rio Tinto Aluminium was in part responsible for its recent adoption by other Australian-based Rio Tinto business units including Northparkes Mines, a copper mining operation in Central New South Wales, and Hunter Valley Operations, a group of four coal mines in the Hunter Valley region of New South Wales. Lean is also being adopted by Rio Tinto Iron Ore. Rio Tinto Aluminium introduced Lean Manufacturing to complement an existing Six Sigma business improvement program and to achieve continuous improvement activities at a workplace level. Lean provides a similar level of rigour and discipline to Six Sigma but its application is everyday and for everyone, everywhere in the workplace. It is a valuable management tool. In a short time, Lean has achieved good and sometimes spectacular results improving productivity and efficiency at all sites, including our mining site. Within Rio Tinto Aluminium, it has also had beneficial impacts on our ability to develop and retain employees.

Jan 1, 2006

By D Eschebach, D Mathewson

A belt press filter (BPF) handbook containing practical information for the reference of plant designers and operators has been created as part of Australian Coal Association Research Program project C23040. The handbook combines research and experience with newer generations of equipment and circuitry. BPFs are increasingly finding application in the dewatering of thickener underflow tailings slurries due to changing environmental regulations, difficulty obtaining tailings storage facility approvals and limited water availability. Sources of BPF inefficiency and low availability stem from a lack of understanding of the key operational parameters that affect their performance. This lack of understanding typically leads to increased operational expenditure due to suboptimal reagent dose rates and increased maintenance costs, or decreases in plant availability due to excessively high filter product water contents and equipment failure. It is essential for the continued economically competitive operation of Australian coal handling and preparation plants that complex factors affecting BPF operational performance are clearly defined and understood. Installation and operation handbooks are often provided to sites with new installations, but these manuals are manufacturer- or even model-specific and are often focused on mechanical maintenance. The handbook identifies industry ‘best practice’ and improvements developed by other sites, such as extra spray bars, air system bleed valves, guarding designs, feed and filtrate protection screens and roller tensioning systems. Equations to predict optimum operating conditions – such as free moisture, belt tension and reagent dose rates, with simple feed-specific variable inputs – have been developed from site-specific test work. The correlations developed provide a benchmark for plants to attempt to achieve. This provides operators and process engineers with a tool to explain BPFs and assist them in optimising the performance of BPF dewatering plants of both contemporary and less modern design.CITATION:Mathewson, D and Eschebach, D, 2015. ACARP belt press filter design, operation and maintenance handbook, in Proceedings Tailings and Mine Waste Management for the 21st Century, pp 73–82 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 27, 2015