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By P Bartsch

Uranium solvent extraction, USX has been applied commercially for recovery and concentration for over 50 years. Uranium in acidic liquor, which is prepared following ore leaching, solid/liquid separation and clarification, can be treated through a sequence of operations; extraction-scrubbing-stripping, to obtain purified liquor. USX has dominated the primary uranium industry as the preferred technological route to converter grade yellowcake. The practices of design and operation of USX facilities has found renewed interest as new mines are developed following decades of industry dormancy. This article seeks to outline principles of design and operation from the practitioner’s perspective. The discussion also reviews historical developments of USX applications and highlights recent innovations. This review is hoped to provide guidance for technical personnel who wish to learn more about good practices that leads to reliable USX performance.

Aug 8, 2011

By Kavanagh M. E, Henley R. W

The Meekatharra mining district lies in the northern pan of the Murchison Province of the Archaean Ynlgam block of Western Australia. Since dis- covery of the Paddy's Flat belt in the district in 1897 total gold production has been 67 tonnes and a further 33 tonnes in resources have been defined by drilling. The Paddy's Flat gold deposits occur within the Gabanintha Formation, a basal formation of the Murchison greenstone sequence containing komatiitic basalts, ultramafics and minor banded iron formations. The regional control on the distribution of deposits is an anastomosing shear belt which extends over 350 km and incorporates the Mt Magnet, Reedys and Meekatharra deposits. The following gold deposit styles may be recognized based on lithological association and alteration: Albite porphyry hosted, Carbonate-fuchsite- quartz alteration hosted deposits, Banded Iron Formation hosted sulphide replacement gold deposits and quartz vein deposits. With the exception of the banded iron formation hosted deposits, the Paddy's Flat alteration zone shows strong similarities to the alteration styles at Kerr-Addison (Ontario).

Jan 1, 1991

The region we call the West Coast is acknowledged as one of the richest and most diverse mineral provinces in the world. It's the most rugged part of Tasmania and our island is one of the most rugged parts of Australia, so that speaks for itself. A hostile land of razorback mountains, deep ravines, dangerous rivers, almost impenetrable rainforests and a climate that can change from mild to freezing in a matter of hours.

Jan 1, 1993

By C Simpson, J M. F Clout, G Plummer

Detrital iron deposits (‘DID’) in the Hamersley Province of Western Australia have been successfully mined and processed as small quantities of saleable standalone or blended lump and fine ore products over many decades. Despite their past, present, and potential future exploitation, they have received far less geological attention than the economically more significant higher grade bedded iron deposits (BID) or channel iron deposits (CID). DID are composed of Pliocene to Quaternary unconsolidated colluvial/alluvial hematite gravels with minor sand, silt, and ferruginous clay, as well as minor iron rich hematite clast conglomerates. DID mineralisation at Solomon has been subdivided into six distinct stratigraphic units, DID-5 (lowermost) to DID-0 (uppermost) based on differences in clast and matrix textures and mineralogy, degree of consolidation/lithification, particle size distribution and replacement textures. The most significant accumulations of DID-1 to DID-5 are in tributary valleys that have been cut through the Joffre Member of the Brockman Iron Formation on either side of the main Kings-Queens valley which contains the CID. DID-5 and DID-4 are ferruginous conglomerate, referred to as canga, with four subtypes recognised. DID-4 is composed of BID hematite clasts cemented by hematite or goethite. DID-5 is characterised by partial to complete replacement of BID hematite clasts and matrix by the yellow ochreous and brown to black vitreous forms of goethite. DID-3 to DID-0 are unconsolidated hematite detritals composed of largely (>80 weight per cent) fine to coarse gravel, minor sand and little silt or clay. The gravel clasts are largely composed of hematite and hydrohematite that replace BID, micro-nanoplaty hematite-martite-ochreous goethite (m-nplH-M-oG) BID, reworked canga, hematite pisoids, siliceous hematite BID (micro-nanoplaty hematite-martite-quartz, m-nplH-M-quartz), chert (~10–20 per cent) and minor (<5 per cent) Banded Iron Formation (BIF). Hematite abundance decreases from DID-3 to DID-0 whilst siliceous hematite BID is highest in abundance in DID-0 and lowest in DID-3. A key finding of the study is that >90 per cent of mineralised detrital clasts are derived from hypogene altered BID micro-nanoplaty hematite-martite with subsequent later supergene ochreous goethite mineralisation hosted by the Joffre Member. The DID genesis model entails interpreted Palaeoproterozoic siliceous hematite hypogene microplaty BID mineralisation of the Joffre Member undergoing Cenozoic supergene leaching of quartz and replacement by ochreous goethite to form low phosphorous BID micro-nanoplaty hematite-martite-ochreous goethite clasts. BID martitenanoplaty hematite-martite-ochreous goethite clasts and detritus eroded from hill slopes were deposited in the valleys as an initial single DID-5-DID-4 unit over a weathered pre-CID basal conglomerate. DID-5 and DID-4 underwent goethite cementation of the matrix followed by replacement by hydrohematite, hematite, and maghemite. DID-3 formed during subsequent periods of erosion of largely DID-4 hematite clasts and pisoids. Groundwater flow-through hematite canga resulted in partial to complete hydration replacement of DID-4 hematite clasts and matrix by ochreous and vitreous goethite to form DID-5. Deposition of DID-2 to DID-0 was via reworking and deposition of DID-5 to DID-4 canga and DID-3 as clasts and pisoids/ooids, as well as siliceous hematite and BIF sourced from the Joffre Member in the hill slopes.

Nov 8, 2021

By D W. Airey

Frictional rock bolts are widely used because of their low cost. However, they have a thin wall section that makes them prone to corrosion, and they cannot be relied on to provide long-term ground support. It is difficult to assess the capacity after the bolts have been installed as they can only be pulled out if this has been allowed for during insertion. The questions of how long can the rock bolts function effectively and the effectiveness of various surface coatings, which can have significant cost implications are, investigated in this study.A series of accelerated corrosion tests have been performed on frictional rock bolts. The rock bolts, typically 900 mm long, have been inserted into concrete cylinders produced using a styrofoam insert to create the hole for the bolt insertion. Strata rock bolts with four surface coatings have been tested: uncoated black steel, galvanised, enduro (plastic coated) and coated with a proprietary aluminium/zinc alloy. Tests have been performed on two diameters of bolts. Following insertion of the bolts, the concrete cylinders were placed in a large drum filled with saltwater and current was applied to accelerate the corrosion process. The rock bolts were then extracted at various times after the commencement of corrosion. Comparison of the insertion and extraction resistances shows that corrosion initially increases the bolt resistance and that substantial section loss is required for the bolt resistance to drop significantly.CITATION:Airey, D W, 2014. Laboratory corrosion tests of frictional rock bolts, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 257–262 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014

By S K. Michelic, N Preisser

For certain applications, steels have to feature a very distinct and well-defined level of cleanness in terms of the number and composition of non-metallic inclusions. Therefore, one crucial aspect of steelmaking is removing and controlling said non-metallic inclusions during the process. Particle removal during ladle refining comprises three stages, namely: 1. Flotation 2. Transport through the steel/slag interface 3. Dissolution of the particle in the slag. Only if all three stages are completed the particle can be considered as fully removed from the steel melt which, in turn, leads to the slag being one of the most influential parameters for inclusion removal and control. Depending on the composition of the particles and the slag, the dissolution can be controlled by different mechanisms. This study focuses on the diffusion-controlled dissolution of solid oxidic particles in slags. For this, a model of particle dissolution has been developed. For modelling diffusion, either the differential equation following Fick’s second law can be solved, or an analytical solution to this equation valid for stationary interfaces can be used. Both approaches allow for calculations of concentration profiles of the dissolving species in surrounding slag. From this, the mass flux can be derived, which finally leads to calculating the boundary layer velocity due to considerations of mass balance. In this work, both methods as well as results of dissolution experiments using High Temperature Confocal Scanning Laser Microscopy are compared. This research aims to provide a framework for diffusion-based dissolution modelling in further expanding the understanding of particle dissolution in secondary metallurgy.

Aug 21, 2024

By B M. Moudgil

Atomic force microscopy (AFM) has become an important tool for understanding the nano- to molecular scale mechanisms predominant in multiphase systems. In flotation research, the use of AFM holds promise for unlocking and establishing fundamental mechanisms, ultimately leading to significant advances in process performance. From measuring and characterising surface forces, the structure of molecules at interfaces, and nanoscale features on flotation media, AFM is a powerful tool that has only begun to impact flotation research. Highlights of advances made in the utilisation of AFM for flotation research at the University of Florida are given with an emphasis on interpreting the mechanisms behind calcium activation in phosphate flotation and the impact of nanoscale asperities on collector-born surface hydrophobicity.

Jan 1, 2005

By M Gill, A Mathias

The mining industry has always been cost-focussed but in recent times mining companies have moved towards obtaining a competitive advantage through the implementation and sustainability of best practice in the areas of improved safety, operating costs, quality and productivity. This is the concept of Value In Use û that mining companies see value generated all the way to the bottom line through improved change, and those changes become an established mine practice. Many mining companies do not have the resources or the knowledge to sustainably achieve such an outcome. This has led to companies looking to their suppliers to deliver measured value to their business through partnership arrangements. Suppliers have been able to leverage their knowledge of products, product applications and services to offer alternative supply agreements that bring greater returns to their businesses while improving supplier/client relationships. Orica has developed such a partnership with Coal & Allied in the form of a Continuous Improvement Program. Coal & Allied is based in the Hunter Valley region of NSW and is the largest coal producer in that region. Both parties are contractually bound to jointly deliver Value In Use projects to Coal & AlliedÆs Hunter Valley Operations and Bengalla mine sites. It is the request of the Orica and Coal & Allied Steering Committees that this paper does not include the details of actual projects or the costs or key performance indicators associated with the program. This is to maintain the competitive advantage to both Orica and Coal & Allied through the implementation of such a program. It is in the writersÆ opinion that this paper does not lose any significance through this restriction as the most important component of the Continuous Improvement Program is not the projects themselves but the methodology behind them. With this in mind the paper will discuss the development of Value In Use offerings, the key aspects of the Coal & Allied and Orica joint program, what is a Value In Use project, how to measure its value, finally why and even more importantly what makes this program is a success.

Jan 1, 2004

By D Smith

The Broken Hill deposit is located in Australia in the far western region of New South Wales. The deposit was found in 1883 and has been mined continuously since its discovery. It is considered the largest lead, zinc, silver deposit that has been discovered in the world and originally contained around 340 Mt of ore at a grade of around 12 per cent lead, ten per cent zinc and 150 g/t silver. The material remaining in the deposit represents only a fraction (perhaps ten per cent) of the original resource. Several of the world’s largest mining companies can trace their origins to the Broken Hill Field. The remaining resources on the CML7 consist of two large lower grade resource lodes that have not been subject to mining, some scattered areas of zinc lode material and the pillars and remnants of the main lead lodes.The deposit occurs in metamorphic rocks of the Broken Hill Group a division of the Willyama Super Group contained within the Curnamona Craton. The Broken Hill Group rocks have undergone multiple phases of deformation. Metamorphism is granulite grade with major shears cutting through the deposit having been retrogressed to mica schists. The deposit lies in an antiform associated with the second phase of deformation.The resultant proposed mine is situated on Consolidated Mining Lease 7 (CML 7) which occupies a strike length of 3.6 km in the central part of the 7.8 km long footprint of the orebody. Underground mining on CML7 ceased in 1975 with surface mining of silver chlorides in the weathered zone continuing until 1991. CBH Resources has been continually working to define and evaluate the remaining resource since 2002. This work has included four surface drilling programs, two underground drilling programs, an exploration decline, enormous amounts of compilation of historical data and detailed three- dimensional (3D) modelling of historical mining and the resource lodes. It is currently planned to commence production at the Rasp Mine in late 2011. The operations will produce from previously unmined lodes and from remnants and pillars.This paper primarily aims to encapsulate the processes involved from information acquisition through to resource estimation and also to highlight some of the challenges encountered and the specific techniques and practices used to overcome them. Many of the experiences at Broken Hill are applicable to all brown field sites.

Aug 22, 2011

Adsorption Behaviours of Humic Substances onto Iron Ore Particle Surface Humic substances extracted from lignite mainly consist of fulvic acids (FA) and humic acids (HA), which have been successfully used as good composite binders for iron ore pellets in laboratory tests and industrial production. However, there exists a general lack of understanding of the interaction between humic substances and iron ore particles surfaces. In this research, by means of zeta potential measurements, Fourier Transform Infrared (FTIR) spectrum, colorimetric method and Environmental Scanning Electron Micrograph (ESEM) imaging, the adsorption behaviours of FA and HA onto the surfaces of iron ore particles are investigated. The zeta potential results indicate that adsorption of FA on the iron ore particles can be characterised by specific and electrostatic interactions, while adsorption of HA is by electrostatic and chemical adsorption interactions. FTIR spectrum results show that adsorption force of FA on the iron ore particle surfaces is stronger than that of HA. From results of colorimetric method, compared with HA, adsorption amount and adsorption rate of FA is more and faster, respectively. FA molecule presents on the surface of magnetite in the shape of an araneose network structure according to the ESEM images, while HA molecule appears on the surface of magnetite in the form of small flocs or microclusters. Humic substances are effective to iron ore pelletisation. Comparsion of agglomeration results show that the different mechanisms of adsorption result in varied agglomeration behaviours. Theses findings above would be beneficial to the implications of composite binder for agglomeration. &nbsp;

Sep 13, 2010

By D Genge, E Martin, T Goswami, M Rothery

Rio Tinto’s Hunter Valley Operations is a large open pit coalmine situated in the heart of the Hunter Valley in Australia. The Riverview West Pit has faced increasing production challenges in recent times due to decreasing dragline strike lengths and increasing environmental constraints on vibration, overpressure and fume generation. Conventional mining techniques would involve five to six production blasts per strip to recover multiple coal seams. Each blast event carries the risk of exceeding the strict environmental requirements. By working collaboratively with Orica, it was realised that the blasting method known as Stratablast™, in conjunction with advanced computer modelling techniques, could provide productivity gains whilst simultaneously providing more control over the environmental effects and the impact on nearby infrastructure.As a result of this change, the number of blasts per strip was reduced to one, with the implication that a great deal of care and forethought was needed to manage the increased challenge posed by multiple constraints in the proposed mining area. This innovative approach of combining throw and stand-up blasts allowed the extraction of all major coal seams in a single pass blast event. The blasts were initially designed with a large factor of safety to stay within environmental limits as they were over 1.1 km in strike length, with more than 800 holes and with a total charge weight of about 1000 t of bulk explosives. Furthermore, there were conflicting priorities around the desired blast outcomes. So far, 11 such blasts have been designed and successfully fired. After each blast, innovative design changes have been iteratively implemented to provide further control over environmental impacts, whilst continuing to improve productivity. As a result of these changes, blasts have progressively increased in complexity with the inclusion of features such as damage zones, mid-splitting, time gaps and different directions of firing. The consequence of this complexity is that the blast duration can be as long as 28 seconds to accommodate all components of the blast.This project has increased the productivity of the Riverview West Pit through blast design improvements and allowed the environmental impacts to be managed with far more control and predictability than would have been possible under a conventional blasting regime. There still remains room for further optimisation of mine productivity and this is being addressed through a process of continuous improvement.CITATION:Goswami, T, Martin, E, Rothery, M and Genge, D, 2015. A holistic approach to managing blast outcomes, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 645–654 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By G McKay, M Erskine, S Macklin

The City of Sydney is currently investing in a number of infrastructure projects that require tunnel excavations within the Triassic Hawkesbury Sandstone. It is generally accepted that this formation has high residual stresses of ‘tectonic’ origin, so much so that these stresses have been implicated in a number of well-known failures and problems for tunnelling. These include failure of ‘roof beams’ comprising discrete beds in the crown of tunnel excavations; stress-induced spalling and ‘slabbing’ of tunnel walls; shear displacement between beds causing the failure of rock bolts; strain in adjacent infrastructure and, the necessity for re-grouting of high conductivity fractures due to stress relief dilation after excavation. Whilst there is an extensive published database of in situ stress measurements comprising ‘hydrofrac’, ‘over-coring’ and ‘slotter’ stress measurements, these data indicate a considerable spread of results. The traditional approach to interpreting this data has been to attempt to fit linear correlations to stress versus depth data, based on personal experience and ‘back-analysis’ of monitoring data during construction. However, there are a number of such correlations in the literature and there is divergence of opinion regarding the assessment of ‘background’ in situ stress and appropriate upper and lower bound values for design. This paper provides a brief review of the published data; suggestions on an alternative ‘risk-based approach’ to assigning in situ stresses for design; and, proposals on how in situ stress tests may be conducted in future to improve the quality of the database available to designers.CITATION:Macklin, S, McKay, G and Erskine, M, 2014. A review of the in situ stress database for tunnel design in the Hawkesbury Sandstone, Sydney, New South Wales, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 171–178 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By T Wellman, G Sternadt, R Hingston

The 335 000 oz Wilber Deposit is located within the Meekatharra-Wydgee Archaean greenstone belt in the Murchison District of Western Australia. The deposit comprises high-grade gold mineralisation hosted within a steeply west-dipping quartz lode, which lies within a broader (20–60?m) north-east striking shear zone envelope. Locally, the northerly-trending host rock geology includes greenschist facies high-Mg basalt (albite, actinolite, chlorite, biotite, calcite, zoisite, muscovite and titanate) intruded by at least two generations of felsic to intermediate porphyries (albite, actinolite, zoisite, chlorite, sericite, biotite, quartz and titanate). The Archaean rocks are cross-cut by a number of east–west striking Proterozoic dolerite dykes (biotite (50 per cent), albite, carbonate, epidote, titanate and actinolite) that are interpreted to have intruded pre-existing regional structures. The entire mine package is cross-cut by a system of shallow north-east-striking, north-west-dipping, barren quartz veins that commonly contain large (up to 30 cm), euhedral, smokey quartz megacrysts.The north-east-trending lode lies within a 3 m wide shear zone and varies from a single discrete 0.5 to 4 m wide laminated, massive or brecciated quartz-carbonate vein to multiple laminated veins up to 1 m wide within the shear. The veins exhibit strong boudinage, with cross-cutting quartz-carbonate seal veins in the boudin necks. The boudin necks often contain pink calcite. The shear zone fabric wraps closely around the boudin necks proximal to the vein, becoming more lode parallel distal to the vein. The lode is offset by a north to north-north-west trending fault.Mineralisation occurs as free gold within the quartz carbonate veins, with accessory sulfides including pyrite ± chalcopyrite, ± galena ± sphalerite. Fuchsite is observed in the veins, as laminar wall rock inclusions, with visible gold commonly associated with the wall rock laminations.Gold grades range from less than 1 g/t within the hosting shear zone, either at the margins or interstitial to the veins, to approximately 30 g/t in the single vein, and up to greater than 60 g/t in the multiple vein areas. Gold is commonly visible and disseminated throughout laminated, breccia and massive quartz veins, although laminations show the highest concentration of gold grains.CITATION:Hingston, R, Wellman, T and Sternadt, G, 2014. The geology of the Wilber Deposit, Andy Well Gold Project, Murchison District, Western Australia, in Proceedings Ninth International Mining Geology Conference 2014 , pp 55–64 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 18, 2014

By F Djukic, T Fisher, G Irving

Questionnaires were sent to 12 underground metalliferous mines in Queensland to enquire how these mines control diesel emissions from mobile diesel engines used underground. Where responses or controls were absent, discussion has been provided. A significant finding concerns secondary ventilation design rates. Some mines were designing ventilation rates to meet the superseded Mines Regulation Act of 1989 which required 0.04 m3/s/kW. The current Queensland Mining and Quarrying Safety and Health Regulation (2001) is risk based. In line with other jurisdictions, including New South Wales (NSW) and most Provinces in Canada, a minimum ventilation rate of 0.06 m3/s/kW is acceptable. However, this design ventilation rate will vary in practice depending on the diesel engines and controls. Dedicated ventilation engineers and technicians should be appointed to evaluate the effectiveness of the ventilation system. Personal exposure monitoring is required to confirm that exposure standards are not being exceeded. The primary control practice should be to reduce the emission at source. This can be ensured by purchasing low emission (Tier 2, Tier 3) equipment. In addition, the use of ultra low sulfur fuel (et al, 2002). Diesel fuel with a low aromatic content such as Eromanga diesel fuel will also mean employees are exposed to lower levels of poly-cyclic aromatic hydrocarbons. These controls should be carried out in parallel with good maintenance practices. Preventative maintenance should be programmed and emissions be routinely tested, including both gaseous and particulate pollutants and compared against defined criteria. According to McGinn, 2002, there are a number of fundamental tools necessary to carry out preventative maintenance. These are outlined in maintenance guidelines and best practices for diesel engines in underground mining produced for the Diesel Emissions Evaluation Program (DEEP). An effective diesel emission management system needs to be fully integrated within the Safety and Health Management System. These requirements are further discussed in this paper.

Jan 1, 2007

By J Li, A McFarlane, J Yu, L L. Kuhar, R Meakin, N Chapman

"Column leach tests are used frequently to predict recoveries and reagent consumption for nickel laterite heap leaches. These column leaches often run for more than 100 days and therefore require long-term monitoring and data analysis to achieve the desired information. To minimise the cost and time required to obtain relevant information for nickel laterite heap leaching, we have developed a small-scale hydrogeometallurgical laboratory test to serve as a proxy to column, and by inference, heap leaching. In excess of 50 leach tests were conducted using four different small-scale proxy and column leach tests to compare predicted nickel recoveries, acid consumption and leach kinetics and to determine whether insight into potential scale-up effects can be obtained. The most promising proxy test was identified and we achieved a statistically significant recovery and acid consumption correlations between this test and the column leach tests. The accuracy of the small-scale tests was confirmed by column tests run on new laterite ores. This geometallurgical proxy could be of use for the population of block models and process selection during the mine planning phase or for optimisation and control during processing.CITATION:Li, J, Kuhar, L L, Meakin, R, Chapman, N, McFarlane, A and Yu, J, 2016. A Geometallurgical Proxy for Nickel Laterite Heap Leaching, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 335–340 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

By H F. Galbiatti, G J. I dos Santos, A de C Zapparoli

The Grao Para and Rio Maria greenstone banded iron formations (BIFs), within the Carajas mineral province, exhibit distinct lithological and petrographic fabrics, together with pronounced differences in their surface expression, real thickness, iron grade and tonnage. These geological differences support a new model for the regional distribution of iron formations in the Carajas Mineral Province.

Jan 1, 2009

By J Jackson, M F. Young

"Ore is the economic portion of a mineral deposit that can be extracted economically. Hence an ore type is a classification of the ore based on one or more dominant characteristics in order to enable communication between unit operations and/or technical disciplines.In project evaluation, ore types are often defined early based on geological observations by geologists and initial metallurgical testing is based around this classification even though a number of processing options can be under evaluation. However, the geological drivers of performance for each of these processes can be very different and the ore type classification for one process may not be relevant for another. In operations an ore type, as either defined in the project evaluation phase or those that evolve with additional knowledge, is unlikely to provide the knowledge required across all the unit operations. The ore type has a meaning to someone but does not necessarily for all unit operations across the value chain.Geometallurgical or orebody knowledge has evolved through the consideration of multiple processes within the value chain, the improved understanding of variability of process performance within ore types and the effect on the complexity of the mineral extraction processes. Furthermore orebody knowledge has been moving from personal based knowledge and understanding to a more process oriented approach where measurement and spatial and process performance modelling is playing a greater role. Advances in mine planning and scheduling allow for both detailed analysis of the block model and the expected extraction processing attributes across various time scales. This capability of analysing and describing the complexity still requires to be communicated to the various unit operations, which may be beyond the traditional classification of an ore type.The limitations of an ore type and potential alternatives to enable the relevant information to be communicated to the relevant groups are outlined through a number of case examples across the value chain.CITATION:Jackson, J and Young, M F, 2016. Ore Type – Everything to Someone but Nothing to Anyone, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 267–274 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

By D Maldonado

BlueScope Steel’s Port Kembla sinter machine underwent a major upgrade during mid-2009. The mixing and rolling drum (MRD) was thoroughly cleaned during the upgrade. Space factor measurements taken in October 2009 showed that the drum was operating in the cataract regime in the dry mixing section and the cascading regime in the rolling section, which is optimal for granulation. Sampling carried out during an entry into the MRD showed that both the Sauter mean diameter and the predicted bed voidage increase rapidly during wetting, and then decrease in the wet mixing section. In the rolling section, the granule properties remained constant untilthe drum discharge. Frozen particle analysis, using liquid nitrogen as the quenching agent, were carried out on material collected from the MRD discharge. The results, expressed as a Granulation Index, showed there had been a significant improvement in the granulating performance of the MRD following the upgrade. The plant studies were also complemented with laboratory scale experiments which aimed to optimise the granulation process. The effect of burnt lime on green feed permeability was quantifi ed using the laboratory scale drum at different moisture contents. A significant increase in permeability was apparent once the burnt lime dosing rates doubled from 1.1 - 2.2 per cent w/w (feed basis). The capacity of the burnt lime system at the sinter machine will be increased in order to benefi t from the expected higher permeability, permeability, which will enable the machine to sinter at deeper bed heights.

Jul 11, 2011

By H von Blottnitz, J L. Broadhurst

Eco-efficiency has been proposed by the World Business Council on Sustainable Development as an environmental performance indicator framework that contributes to sustainability by assisting corporate decision makers improve the environmental performance of their operations and processes, while also extracting additional economic value. Given that the recent engagement of the minerals industry with sustainability has highlighted the need for requisite tools and methodologies, it is therefore of interest to assess whether eco-efficiency indicators can drive sustainability performance improvement during process design within the minerals industry. Previous work indicates that the choice of sustainability performance indicators to be used for decision making needs to be governed by the decision context; ie the performance indicators need to be fit-for-purpose. Here, the strengths and weaknesses of eco-efficiency indicators are analysed using case studies. First, a more rigorous definition of eco-efficiency indicators for the minerals industry is proposed based on indicators currently offered in the literature. Two case studies are then selected to reflect typical decision situations encountered within minerals process design. For each case study, eco-efficiency indicators are computed and are compared to more traditional graphical representations of the economic and environmental performance of process design alternatives considered. The sensitivity of these indicators to various process design parameters is also investigated. Results confirm that the meaningful application of eco-efficiency indicators is strongly dependent on the decision context in which the process data is generated. Results also show that eco-efficiency indicators can be related to technical process design parameters to allow for richer communication of performance information for various decision trade-offs; however, in some cases, graphical approaches that provide more insights into the environmental-financial trade-offs should be preferred. The research thus contributes to guiding the selection of the appropriate tools for more environmentally sustainable design of minerals beneficiation processes.

Jan 1, 2009

A number of gases, such as carbon dioxide, methane, water vapour, nitrous oxide, ozone and chlorofluorocarbons are transparent to incoming short-wave radiation, but are relatively opaque to outgoing longwave radiation. Variations in the concentration of these gases in the troposphere can alter the thermal balance of the earth&apos;s atmosphere. Outgoing terrestrial radiation which would otherwise escape to space, is trapped within the inner layer of the atmosphere, resulting in a greenhouse effect. It is estimated that at present greenhouse gases other than carbon dioxide, contribute about 50% to the greenhouse effect. However, in the future, the contribution made to the greenhouse effect by gases other than C02 will become increasingly more significant. Greenhouse gases arise from a wide range of sources and their escalating increease is largely related to an increase in the world&apos;s population, an increase in the standard of living of many areas and changes in lifestyle. The effect of increasing man-made greenhouse gases in the troposphere is unknown but it is proposed that it may increase temperature and may modify climate, agricultural response and land use. The sources of greenhouse gases are identified and found to comprise a wide range of activities. The contribution that coals use makes to the greenhouse effect is examined in detail. It is concluded that coals total contribution is small being about 10% of man made greenhouse gases. Envisaged expansion of coal&apos;s use will only cause a small increase in greenhouse gas emissions. Whilst developing technology for coal&apos;s use for power generation has the potential to reduce greenhouse gas emissions from new plants by approximately 25%.

Jan 1, 1989