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By Houyuan Liu

A new process was developed to recover nickel and cobalt by leaching laterite ore at atmospheric pressure and.95"-105" C. The nickel-containing goethite in limonite was first leached with sulphuric acid to liberate over 90% of nickel, cobalt and iron. The dissolved iron was then precipitated as Ni-free goethite by the additioil of saprolite. The acid released during iron precipitation as goethite was simultaneously used as lixiviant to leach saprolite to recover more nickel. With this process the limonite and saprolite were essentially converted into goethite-, gypsum- and silica- containing tailings. Twenty bench scale tests and two campaigns of pilot plant operation were carried out at BHP Billiton's Newcastle Technology Centre (NTC) from January to August 2002. The overall nickel and cobalt extractions were 81 to 90% and 91 to 100% respectively. The average plant availability was 99%. The advantages of this process over existing processes include high plant availability, high consistency, robustness and simplicity of the operation.

Jan 1, 2004

The current boom being experienced by mining, coupled with a shortage of professionals, will mean those in the industry will have many choices. It may be easy to become carried away and run with the highest bid or the biggest promise. Without planning, however, the ærightÆ opportunity may be missed and there may be some long-term consequences. There are many choices of paths in the industry to suit work preferences, life cycles and to achieve a balanced life. People in mining have changed jobs and companies frequently û which means new leaders need to take greater responsibility in charting their own direction. Career options need to be carefully assessed and aligned to personal values and preferences. Emphasis is given on gaining site experience early on.This paper examines strategies for career planning, which incorporate life cycles, education and what is meant by a balanced lifestyle. Two tools are identified as being helpful in ensuring strategies can be successfully executed. They are ævisioningÆ and æinfluenceÆ.To make the mining industry more attractive, we need more creative solutions around advances in technology and organisation of work. It also needs the input and leadership of new entrants in to the industry to assist in its survival. New leaders are encouraged to voice a vision and effectively influence their companies. New leaders have little authority and need to learn how to effectively influence. We as a mining industry need to listen, be open-minded and give it a go.

Jan 1, 2004

By Blas Melissari, Stavros A. Argyropoulos

"In this paper a computational approach was employed to estimate the melting of solid spheres immersed in different liquid metals and under different convective conditions. The spheres are made from the same material as the liquid metal. The SIMPLER algorithm was implemented using a three-dimensional system in Cartesian co-ordinates. Experimental validation of the dimensionless correlation was carried out in two fluids with vastly different Prandtl numbers. The dimensionless heat transfer coefficient (Nusselt number) is obtained as a function. of the Reynolds and Prandtl number.IntroductionThere is a paucity of dimensionless convective heat transfer correlations applicable to fluids like liquid metals. The existing correlations cover single Prandtl number metals [l] or at most two different Prandtl number metals [2]. A knowledge of heat transfer rates from particles at high flux levels has become increasingly important to the design of energy transfer systems. Melting of solid particles has been studied extensively as it relates to many engineering and environmental applications, such as materials processing, space applications, water resource and energy conversion. When objects are immersed in a fluid with a temperature higher than their melting point, they melt and produce molten material that then mixes with the surrounding fluid. These objects experience not only size variation but also changes in their shape. This observation is more pronounced when the melting occurs in a forced convective flow.Yuge performed pioneering experimental work on the heat transfer from a sphere to air under mixed convection [3]. He suggested procedures for predicting the Nusselt number. Hieber et al [4] studied the spherical system analytically, but their study was limited to flow with small Reynolds numbers. Many researchers studied the melting dynamics of ice spheres in water at different convective regimes. Aziz et al [5] and Hao et al [6] performed measurements of the heat transfer coefficient in the water system by measuring the melting time of ice spheres in forced convection. Hao et al [7] performed visualization studies of ice spheres melting in water under mixed convection regime. All of this groundbreaking work, however, did not involve the use of liquid metals"

Jan 1, 2004

Leaving the relatively simple life on a uni student and venturing off in to the outside working world is a big step. There are two paths to follow, the æContikiÆ style graduate program where you pick up your new lease vehicle and set forth on two to three years of planned activities, or can pack everything into one bag, stick a copy of æthe rough guideÆ in your pocket, and set off on your own graduate adventure. I took the path less travelled.The less followed method of developing yourself isnÆt for everybody. Parts of the journey are difficult and sometimes it feels hopeless, but itÆs all a learning experience. Along the way you might not get to all the graduate ætourist stopsÆ like dragline, truck-shovel, or drill and blast. But youÆll see most of them and pick up a lot more of the local culture such as people management, operational knowledge, quality control, and the black arts of project financial management.

Jan 1, 2004

By Debbie Marshall

Nickel and cobalt in lateritic ores can be extracted by either a hydrometallurgical or a pyrometallurgical route. The high-iron limonitic fraction of a deposit is best processed' hydrometallurgically while the magnesium-rich transitional and saprolitic fractions are more suited for pyrometallurgical processing. During hydrometallurgical processing, it may be attractive, for economic reasons, to blend the limonitic component with transitional and saprolitic ores, which contain higher nickel levels. However, blending increases the concentration of magnesium in the feed, leading to increased acid demands. The decision on how much ore to process then becomes an economic one. Ore samples with different magnesium contents were prepared for the leach test program by blending limonitic and transitional ores. The ore samples were slurried in seawater and tested in the Falconbridge Hydrometallurgical Pilot Plant. As expected, acid consumption increased with increasing magnesium content of the ore. For target extractions of 95% nickel and 92% cobalt, the required residual free acid concentration increased from 30 g/L at 1.7% magnesium to 50 g/L at 2.7% magnesium. When the magnesium content was raised to 3.8% and 4.6% in subsequent pilot plant testing, the final free acid requirements did not increase beyond what was observed at 2.7% magnesium. Thus, the cut-off ore composition to maximize nickel units and minimize acid requirements is between 1.7- 2.7% magnesium. Keywords: high pressure acid leaching, laterites, magnesium

Jan 1, 2004

Pilot plants for pressure hydrometallurgy represent special design and project execution challenges unique to the industry and to the pilot- and demonstration-scale. Pilot plant projects have different objectives and shorter timescales than commercial plant projects. Design considerations and strategies, and project execution methods that meet the special needs of pilot plant projects, are discussed. Specific guidance is given for the selection of appropriate pressure and temperature design points for pressure hydrometallurgical process equipment, and for the selection of materials of construction for pilot-scale equipment. The balance between the need for process similarity with future commercial operations and the realities of pilot-scale equipment is also discussed.

Jan 1, 2004

By S E. Wallah, D Hardjito, B V. Ran

The manufacture of Ordinary Portland Cement (OPC) is not only energy-intensive but also releases a significant volume of carbon dioxide (CO2) to the atmosphere. In addition, OPC in concrete often causes premature deterioration that affects the durability of concrete structures. This paper explores an alternative to OPC concrete called geopolymer concrete.The present research utilises low calcium (class F) fly ash as the source material to produce geopolymer concrete. Several factors that affect the mix design process such as mix proportion, curing time, and curing temperature have been studied. In addition, the long-term properties such as drying shrinkage, creep, and exposure to sulfate attack are also being investigated.The test data presented in this paper reveal that geopolymer concrete possesses high compressive strength, undergoes very little drying shrinkage and moderately low creep, and shows excellent resistance to sulfate attack. The result is extremely promising and demonstrates the sustainability of geopolymer concrete as a construction material for a sustainable future.

Jan 1, 2004

By P Aguilera, C Guerrero, M Tucker

With the advent of Electronic Detonator Systems in the global mining industry, as well as the development of high precision pyrotechnic delays, the measurement and analysis of delay performance (usually measured in terms of dispersion about a batch mean û precision, and the deviation of that mean from the nominal detonation time û accuracy), has become an important issue. Through the non-conventional use of existing Velocity of Detonation (VoD) measurement technology, it has been shown to be feasible to measure the precision and accuracy of delay detonator series connected in the same manner as a typical open pit bench hook up. This paper describes the work undertaken to compare and contrast performance results obtained using a range of instrumentation including High Speed Video (HSV) filming, digital counter timing using a Hewlett Packard Universal Counter and a digital VoD measurement device. The results obtained demonstrated the practical feasibility of using the latter technology in order to obtain relatively large amounts of data in a time-efficient manner, with a precision of better than 0.5 microseconds, if required. The results also confirmed the close statistical agreement obtained between the three forms of performance measurement, therefore permitting the substitution of the VoD measurement technique for the more capital cost intensive HSV technique and the slow, sample-by-sample HP Universal Counter method. This paper describes the methodology applied and the results obtained.

Jan 1, 2004

By W. Pietsch

For a number of reasons, solids entering and leaving facilities for the treatment of minerals are becoming increasingly finer. Such materials pose problems throughout processing. Solids featuring small particle sizes tend to dusting, result in losses and segregation, exhibit various storage, transportation, and metering problems, and fine particulate effluents can not be easily captured, used and/or recycled. Sustainable mineral processing must minimize the exploitation of natural resources and avoid the need for disposal of wastes. The first requires the use of lower quality raw materials and upgrading, which typically results in the production of fine grained concentrates, and the latter encourages the recycling of wastes and byproducts or efforts to investigate them as sources for secondary raw materials or other beneficial applications. To overcome the difficulties associated with fine particulate solids, size enlargement by agglomeration is necessary. The resulting products have free flow characteristics, do no longer dust or segregate, and are sized and shaped as required for optimum processing. In addition, agglomerated materials may be engineered to feature desirable structure, composition, and a number of related, improved properties. Such engineering may be applied for the modification of fine run-of-mine and up-graded minerals as well as the production of secondary raw materials from by-products or wastes. By the interdisciplinary application of size enlargement by agglomeration waste-free processing of minerals becomes feasible.

Jan 1, 2004

By P. T. O'Kane

The PLATSOL® process, initially developed for the treatment of the NorthMet Cu/Ni/PGM concentrate, has seen over the recent years its applicability extended to include numerous other Cu/Ni concentrates of the same type, as well as other precious metals-containing feedstocks. However, several concentrates were found refractory to the typical PLATSOL® conditions, more particularly so the platinum. Attempts to extend those conditions, such as higher temperatures (250°C), longer retention time, increased oxidation conditions, higher chloride additions, were not successful. Detailed mineralogical investigation of those PLATSOL® leach residues indicated the main refractory mineral to be cooperite (PtS). Further metallurgical investigations showed that a thermal pre-treatment of the concentrate effectively unlocked the refractory platinum minerals for the subsequent leach. Temperatures between 400 and 750°C were tested, with the optimum being found around 650°C. The kinetics of the pre-treatment process were fast, and one hour at temperature proved sufficient. Under those conditions, PLATSOL® extractions were re-established around 95% for both platinum and palladium. From a mineralogical examination of the calcine, it was shown that the effect of the pre-treatment was to transform the cooperite and other refractory sulphides into metallic platinum and alloys, amenable to the PLATSOL®. The implications of the pre¬treatment step for the processing of PGM concentrates arc briefly discussed.

Jan 1, 2004

By G. Zárate, G. Tapia

Anglo American Chile has been doing copper concentrate leaching studies at the laboratory and small pilot plant scale since 1992. Among the processes evaluated are bacterial leaching and pressure leaching using Mantos Blancos, Salobo Project and Quellaveco Project concentrates. Late in the nineties, it was decided to focus the research on pressure leaching, either medium or total pressure oxidation. Preliminary scouting tests were run with Mantos Blancos concentrate samples during 2000, which were repeated during 2003 together with samples of Los Bronces and El Soldado concentrates, in order to define the most suitable concentrate for running a pilot plant campaign at AARL, which was carried out in two campaigns, a first one from November 2003 through January 2004 and a second one during April 2004. Mantos Blancos was the selected concentrate and the laboratory and pilot plant results are discussed in this paper together with some preliminary economic estimates.

Jan 1, 2004

Continuous improvement in environmental management assists in the achievement of sustainability goals for the processing of minerals. The use of regular internal environmental audits (scored or unscored) which form an integral component of an Environmental Management System (EMS), provide demonstrable evidence of this improvement. Case studies are presented for a number of major coal mines in the Hunter Valley, where regular internal environmental audits have been undertaken every two to three months, over periods varying from 18 months to five years. Examples of the benefits of improved environmental performance (driven by the audit process) to sustainable development are provided.The auditing process as described here for coal mines, and coal handling and preparation plants, is equally applicable to the processing of other mineral ores, metalliferous mines, quarries, and oil and gas projects.

Jan 1, 2004

By J. R. Kiji

The Cerro Matoso S.A. mine and smelter, in the Cordoba lowlands of northwestern Colombia, consist of a dedicated laterite nickel mine, ore blending, drying and an RKEF process to produce high-quality ferronickel. At a project investment of $400M, first production of ferronickel was in September 1982, and in its inaugural year CMSA produced 6,150 tons of contained Ni from a mined ore grade of 3.2% Ni. Initial operational difficulties resulted in a number of furnace run-outs, which impacted ramp up to design ore throughput of 128 dry t/h Since then CMSA has steadily incorporated process improvements and initiatives to take the single line operation to an ore throughput of 175 dry t/h. A second 175 dry t/h line was added in 2001 (investment of US$ 300M) to consolidate CMSA as one of the world's lowest cost Ni producers with an installed annual production capacity of 50-55,000 tons Ni. The most recent addition is commissioning of Phase I of an ore-upgrading project to counteract the effect of declining ore grades. Keywords: Laterite, ferronickel, pyrometallurgy, smelter.

Jan 1, 2004

By M D. Urbani

HiTec Energy Ltd has been conducting research since 1996 into novel process routes for the treatment of low-grade and waste manganese sources for the production of high value and high quality electrolytic manganese dioxide (EMD) for the alkaline battery market. HiTecÆs approach is to treat previously unsaleable manganese deposits and mine site tailings using a novel sulfur dioxide leach route, followed by purification and electrowinning to generate the sought-after EMD product by an environmentally superior processing route to those presently practiced throughout the world today.HiTec Energy Ltd expects to be in commercial production with its Stage 1 facility in Kalgoorlie in the last quarter of 2004 for the production of 12 500 tpa EMD. With this production facility being adjacent to a laterite nickel producer with available waste manganese units, the opportunity arose for HiTec to combine its existing technologies with processes (that will be discussed in this paper) to turn two waste by-products into products that are used for high-tech purposes.HiTec Energy Ltd and the Parker Centre have had a collaborative research relationship for a number of years in areas involving EMD and battery related technologies. Meanwhile the solvent extraction (SX) group of the Parker Centre (CSIRO Minerals) has developed SX processes to separate manganese from nickel and cobalt. A project was initiated by HiTec Energy to recover manganese from waste laterite leach solutions using SX technology. Batch tests were conducted to select a suitable organic system for the extraction of manganese in terms of selectivity and extraction and stripping kinetics.A total of eight organic systems were tested by determining pH isotherms of metals using a laterite nickel process waste stream. Two organic systems, the Versatic 10 and Versatic 10/synergist systems, were chosen for further test work with Shellsol D70 chosen as the diluent for both systems.The Versatic 10/synergist system would be advantageous over the pure Versatic 10 system because fewer SX stages are required, resulting in a smaller organic inventory and lower capital costs. The risk of gypsum formation is also significantly lower with the synergistic system.

Jan 1, 2004

By K. Rainer Massarsch

"Part 1 of 2 By K. Rainer Massarsch, Geo Engineering AB, Stockholm, SwedenINTRODUCTIONConstruction activities, such as driving of piles and sheet piles, soil compaction or excavation generate noise and vibrations. In populated areas these can have a negative impact on the environment, disturb inhabitants and, under unfavorable conditions, cause damage to buildings and installations. This condition is aggravated by the growing public awareness of environmental issues and the increasing use of vibration-sensitive electronic equipment and machinery in industry. In many countries, environmental regulations are enforced more stringently and limit or even prohibit the use of impact or vibratory hammers. This development has restricted the use of cost-effective foundation methods, such as driven and vibrated piles and sheet piles.Vibration problems are gaining importance in many European countries and extensive research has been performed during the past decade, especially with respect to traffic vibrations (Massarsch, 2004). Significant progress has been made owing to the availability of high-quality field measurements and an improved theoretical understanding of how vibrations are generated and transmitted through soil layers. These findings can also be applied to vibration problems associated with construction activities. However, this information is not yet appreciated by the geotechnical profession and even less by the construction industry.This paper discusses the effects of ground vibrations on the surrounding soil and on buildings, with particular emphasis on the different mechanisms of damage that may occur. Guidance is given on the elements which should be taken into account in an assessment of risks associated with piling projects. A simplified method is proposed for assessing the risk of settlements or strength loss in soil deposits. Limiting vibration levels are presented, based on the Swedish standard, which can be used to assess the risk of damage to buildings. Aconcept to predict ground vibrations caused by pile driving and the mechanisms which control the propagation of ground vibrations, will be presented in the second part of this paper."

Jan 1, 2004

By Sven-Erik Johansson, Gosta Rundqvist, Donald Jonson

In Stockholm a new road traffic system called Södra Länken (Southern Link) will be in operation in late 2004. The total length of the road system is 6 kilometres of which 4,5 kilometres run through tunnels under suburbs immediately south of Stockholm inner City. The new traffic tunnels together with existing Metro tunnels, which mostly are in rock, will be the determining factor for blast design for many projects in the future. To set reasonable and safe permitted vibration levels the Swedish National Road Administration, Stockholm Region and Stockholm Transport Rail System have together financed a project to determine guide levels for blast-induced vibrations in traffic tunnels in rock. The purpose of the project has been to establish guide levels that are appropriate for different types of rock tunnels.

Jan 1, 2004

Bacterial leaching of sulfide minerals are fairly well established in heap, dump and in situ leaching and the primary bacterial treatment of refractory gold concentrate using CSTR have gained industrial prominence in recent years. Three cultures, a mesophile T ferrooxidans (DSM583), a moderate thermophile Sulfobacillus acidophilus (strain YTF1) and a extreme thermophile (Sulfolobus strain BC65) were used for the biooxidation (pre-treatment) of the Porgera gold-bearing pyrite concentrate under optimum O2 and CO2 enriched air (30 per cent O2 and ten per cent CO2) based on volume ratios. The positive effect of using oxygen and carbon dioxide enriched air for the biooxidation of gold-bearing pyrite mineral was clearly demonstrated where an increase in Fe release rate by a factor of 2.8, 1.8 and 1.5 for DSM583, YTF1 and Sulfolobus respectively were observed compared with the shake flask tests. The lag phase observed with the other test conditions such as in shake flask or with air decreased by about 80 per cent for all three cultures. The average observed dissolved oxygen concentrations in the pulp for these tests were 8.7, 5.8 and 5.0 mg/L for DSM583, YTF1 and Sulfolobus respectively, indicating that O2 was not limiting in these tests. The pulp redox potential was observed to increase with time for all tests coincident with the leaching rate and reaching a maximum of 663 mV, however the maximum value differs for each strain, with DSM583 exhibiting the highest followed by YTF1 and Sulfolobus. Biooxidation of pyrite under optimum gas enrichment at different pulp densities showed near total Iron extraction occurred for pulp densities of three, ten and 20 per cent (w/v). At high pulp densities, more so at 40 per cent than 30 per cent (w/v), the leaching rate decreased rapidly for tests with YTF1 and Sulfolobus. Monitoring of dissolved O2 shows that O2 demand increased with increasing pulp density and the average dissolved O2 concentration observed for YTF1 and Sulfolobus at 40 per cent solids concentration was 1.0 mg/L and below, suggesting limiting oxygen and carbon dioxide conditions for these two cultures. The decrease in leaching rate observed at high pulp densities (30 and 40 per cent) under optimum gas enrichment was accompanied by low metal dissolution and low redox potential values which was attributed to shear stress due to attrition of cells by high solids concentration, toxicity of metal ions especially Ag and Fe and the formation of precipitates and jarosites as confirmed from XRD analysis of leach residues hence impeding the leaching process. Limiting conditions due to high pulp density and viscosity were only observed for YTF1 and Sulfolobus. The subsequent cyanide leaching for precious metals from the pre-treated pyrite concentrate in all cases shows the extent of gold and silver recovery increased with the degree of pyrite oxidation and Au and Ag recoveries in excess of 80 per cent were achieved compared with only 18.1 per cent and 35.9 per cent for gold and silver respectively when treated by direct cyanide leaching on the original, untreated concentrate.

Jan 1, 2004

By A J. Minns

This paper addresses the question: how can the minerals industry remain viable; viable in the sense that we are able to access land for exploration and discovery, we are able to develop and operate mines (and processing plants) safely and profitably and we are able to close operations in a responsible manner, so that modified landscapes are restored to acceptable community standards?Many of the answers to this question can be addressed through the theme of this conference û that of eco-efficiency. The eco-efficiency concept is very useful, since it does help to translate principles of sustainability into business value at the operational level. To provide some context to how this can be achieved, the paper discusses what is happening at the international level, outlines some key industry initiatives within Australia and then discusses what work is being done within companies.

Jan 1, 2004

By S Wotherspoon

At Kalgoorlie Consolidated Gold MineÆs (KCGMÆs) Fimiston Operations, located on the periphery of Kalgoorlie Boulder in Western Australia, roughly 7.5 million tonnes of rock are broken each month for the extraction of gold. With the close proximity of neighbours to the mining operations in the Chaffers Cut Back, special blasting techniques and tools were employed by KCGM to manage the blast induced vibrations and noise in this area. The i-konTM initiation system coupled with OricaÆs complementary modelling and analysis tools offered the complete blast management package. With these tools KCGM management and Orica Mining Services commenced an investigation into the benefits of electronic initiation. Prior to the commencement of electronic blasting, initial modelling was conducted to examine the vibration time waveforms and their frequency content, as these were expected to have an impact on vibration interaction with structures such as large buildings and urban dwellings. This work looked at results measured for a previous conventionally (pyrotechnic) initiated blast in the area and compared it to the results obtained when the blast was modelled with electronic initiation and faster timings. The predicted peak particle velocity (PPV) and structural vibration factor (SVF) were calculated. From the results it was concluded that the investigation into using i-konTM electronic initiation system and SHOTPlus«-i blast design software had some real potential to improve blast vibration management on the cut back. The use of the electronic initiation system and complementary software allows intricate timing designs to be accurately placed into blasts. The system has a number of working modes that allow either the precise design timings to be logged automatically into each detonator or to be manually logged where a variation from the design exists. Where such variations from the design occur, the electronic system permits the actual timings used to be uploaded back into the design file. This allows both design and real actual timings to be stored for future analysis or reference.

Jan 1, 2004

Organisations are starting to develop processes for achieving sustainability principles they have defined for their organisation. The foundation for these principles is now well accepted. The definition of a sustainability framework is a good starting point for any project. The delivery of the framework requires the organisation to think differently about how project objectives can be met. New tools are becoming available to help achieve the sustainability outcomes for the projects. This paper will examine the project building blocks that are necessary to ensure the sustainability framework can be achieved for the project. These include new approaches to decision-making processes and evaluation tools and when to apply them. An integrated approach with shared expertise to project delivery, which is applicable to the whole supply chain, will be discussed. This will cover sustainability procurement, integrated waste management, cleaner production and eco-efficiency, sustainable products and disposal. A project toolkit will be presented and some key project tools identified. The need for management support in undertaking these new approaches is critical, as is the need to develop partnerships and cooperative management to facilitate delivery.

Jan 1, 2004