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By K L. Brown

Sampling and analyses of deep waters from Wairakei and Rotokawa geothermal systems indicate a wide range of precious metal concentrations (<0.1 to 23 ppb Au; 6 to 2400 ppb Ag), suggesting that eastern ôandesiticö TVZ geothermal systems (eg Rotokawa) have higher aqueous gold and silver than western ôbasalticö geothermal systems (eg Wairakei); this interpretation is consistent with known occurrences of high grade precipitates in wells from eastern systems. The fact that the deep waters are undersaturated in gold further suggests that the aqueous gold concentrations of deep waters are limited by metal availability. The flux of gold for the two systems ranges from ~1 to 50 kg Au/yr, and the flux of silver ranges from 65 to 6900 kg Ag/yr. At Rotokawa, it only takes ~600 years to flux one million oz of Au and >100 million oz of Ag. The supply of hydrothermal gold and silver is obviously important during genesis of an epithermal deposit, but ore formation also depends on the existence of a suitable ôtrapö that efficiently extracts metal from solution in a small volume of rock. Such traps seem to have been poorly developed until geothermal drilling in the TVZ.

Jan 1, 2006

By S Hapugoda, J R. Manuel, M J. Peterson, A Poliakov, E Donskoi

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Aug 12, 2013

By S Schwarz, D Alexander

The mining industry, and in fact the world, has undergone significant changes in the past five to ten years, ranging from the metals boom, the global financial crisis and the rise and fall of national economies, to name just a few. There has been a focus on sustainable development for projects and operations in the mining industry, mainly pushed onto the industry by communities, governments and other agencies. While sustainable development and operation is a worthy priority for mining operations, discussions with mining industry personnel (with a strong slant on the mineral processing perspective) have shown other issues have surpassed the typical issues of water resources, energy availability and the environment. These include staff turnover and skills shortages, extracting metal from more complex orebodies and the uptake of new step-change technology.A number of key operating mineral processing personnel were interviewed to determine their perspective on the current issues facing the mining industry. This paper details the findings of this survey and highlights some of the topics that have been identified as the top issues from a mineral processing perspective.CITATION:Schwarz, S and Alexander, D, 2012. Current issues in the mining industry - From the operational mineral processorÆs perspective, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 369-372 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By J Harris, M Shi, S Vink, P A. Kirsch

Across the life-of-mine, water is both an essential commodity to mining, and one of the most significant hazards. In Australia, a land of drought and floods, availability of water is a critical strategic risk for mine sites and neighbouring stakeholders, with both insufficient water leading to curtailed operations and contested space, and extreme water closing operations through flooding of mine sites, transportation infrastructure and unplanned regulatory restrictions. In addition to these major strategic risks, water must be addressed in operational risk management activities in many different ways.This paper develops a set of categories for classification of water risks based on academic papers from the water in mining literature. These categories are applied to media content analysis of articles in International Longwall News (ILN) (an online coal industry news site) obtained with the search terms ‘water’, ‘rain’ and ‘flood’. Identified risks are discussed within the context of the life-of-mine. The paper uses these same categories to analyse the treatment of water risks in a new coal industry risk management body of knowledge called RISKGATE (http://www.riskgate.org, Minerals Industry Safety and Health Centre, The University of Queensland). The discussion of water risks in both INL and RISKGATE is compared and contrasted to pinpoint opportunities (and a roadmap) for further development of a specific RISKGATE water module for site-based operations. The media review also identifies areas for development of RISKGATE expansion topic(s) that would address other strategic water risks, eg severe weather events.CITATION:Shi, M, Kirsch, P A, Vink, S and Harris, J, ?2014. Water as risk in mining – media analysis and the RISKGATE body of knowledge, in Proceedings Life-of-Mine 2014 , pp 205–218 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 16, 2014

By P J. Handley

"Predicting how coal seams will be beneficiated through the coal handling processing plant (CHPP) has long been challenging within BHP Coal. Various coal seams from different areas are mined and stockpiled separately, often depending upon a deleterious coal quality parameter; high/low trace elements for example. These stockpiles are then fed in different ratios into the CHPP to produce the desired product/s. In understanding the washability characteristics of the feed source, mine geologists and process engineers work together to improve the beneficiation of different coal materials through the CHPP.For the majority of the BHP Coal deposits, the washability data is available for the coal seams across the deposits. However, no previous standardised modelling and prediction technique existed that could ensure the correct information was available for forecasting and refining CHPP processes. This paper will discuss the steps undertaken to implement a geometallurgical prediction tool that simplified and streamlined the washability modelling and yield estimation process. The value realised to the BHP Coal assets resulting from this process was: improved compliance to plan increased throughput increased CHPP recovery through improved efficiencies and increased revenues.CITATION:Handley, P J, 2017. Washability modelling and estimation techniques used to improve coal handling preparation plant beneficiation, in Proceedings Tenth International Mining Geology Conference 2017, pp 327–336 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Sep 20, 2017

The demand for gallium has increased significantly over the last few decades due to the expanding use of Ga compounds in the electronics industry. Because it is widely dispersed and rarely found naturally in concentrations greater than 0.1%, Ga is expensive (approximately US$500/kg) and difficult to produce in large quantities.   A previous study of metals in geothermal systems reported significant quantities of Ga present in the muds on the northeast margin of Lake Rotokawa, an acidic lake associated with a high-temperature geothermal field situated in the Taupo Volcanic Zone of New Zealand. Similar muds are present in many other geothermal fields in the zone, suggesting that geothermal muds could be a commercial source ofGa.

Jan 1, 1994

Open pit mining at Bingham Canyon commenced in 1904 and about two billion tonnes of ore have been extracted since then. There remain just under one billion tonnes of ore in the pit and this will be mined by 2015. Because the porphyry system extends below the ultimate pit limits, Kennecott Utah Copper Corporation initiated a study in 1997 to determine the viability of underground mining. The study was initiated at that time because the results were to be used to compare the economics of a further pit expansion to that of an underground mine. If a pit expansion was viable then overburden removal would have to start in the near future. This paper is a summary of the work that was carried out for the underground study. Block cave mining was determined to be the most appropriate method to mine the deposit. Two block cave areas have been planned with a total production rate of 72 500 tpd. Additional sources of ore will come from skarn orebodies that are associated with the porphyry deposit. The geology of the deposits is described together with the geotechnical techniques that were used to characterise the rock in the absence of more detailed data that are normally available. A general description of the mine plan is given along with the reasons for selecting the particular methodology used. The study was completed at the end of 1998 and demonstrated the viability of underground mining at Bingham Canyon. Funds have been approved for further drilling and technical studies, which will lead up to a feasibility study in 2004/5.

Jan 1, 2000

By N Eriksson

BolidenÆs Aitik mine, located 100 km north of the Arctic Circle in northern Sweden, is one of EuropeÆs largest copper mines. This operation produces 18 Mt of ore per year and 99 per cent of this tonnage needs to be deposited as tailings. The tailings pond currently covers 1140 ha but at closure it will hold around 760 Mt of tailings and occupy an area of 1400 ha. The tailings contain less than one per cent sulfur and only 0.03 per cent copper. The carbonate content is as low as 0.25 per cent but silicates, with substantial accumulated buffering and metal adsorption capacity, are abundant. A programme of comprehensive material characterisation and investigations has been undertaken in order to design a decommissioning strategy that meets the regulatory requirements and secures long-term physical and chemical stability of the deposited tailings. The main concern has been the potential generation of acid rock drainage (ARD). Standard tests using acid base accounting (ABA) and humidity cell tests during 15 weeks were not conclusive regarding the ARD generation potential. The accuracy of the results was considered to be unsatisfactory, therefore the humidity cell tests were gradually extended in time. In total, almost four years of humidity cell tests were conducted on various sets of samples which were selected in order to cover the variation in sulfide content existing on site and in various points of the milling process. The laboratory results were subject to detailed geochemical evaluation in order to fully understand the interaction between acid-producing reactions, driven by weathering of sulfides, and acid-consuming reactions by dissolution of carbonates and alumino-silicates. The laboratory tests were followed by both pilot tests and field measurements in order to estimate the scale dependency between the laboratory and the field results. It was found that sulfide weathering rates in the field were considerably lower than those measured in the laboratory. However, it could not be verified that the tailings top layer would maintain a neutral pH in the long term even under field conditions. Thus, a reviewed tailings management plan, including de-pyritisation of the tailings during the last years of operation, is considered.

Jan 1, 2003

By E Wargem

The optimum mining of an orebody in an underground mining operation is fundamental to the mine’s ability to operate both sustainably and efficiently. The effective mining of an open stope or a cave is largely reliant on the recovery of the initial void created by conventional drilling and blasting. These initial voids are known by various names such as a Longhole Rise, Slot or Winze and can be mined either as a downhole or as an uphole. Regardless of the underground mining method, the process of the design and implementation of this initial void is largely uniform across many operations with various patterns of slot or winze designs used across these different operations. Diligent design, implementation and review strategies in drilling and blasting of these will facilitate cost-effective mining with minimal disruption to mine schedules and production targets. When an operation struggles in opening the initial void in underground mine blasting, it has a negative impact on productivity, mineral recovery, and the overall economics of mining. Near field blast vibration monitoring is a vital tool to use in analysing slot blasts and will provide additional feedback into the reconciliation part of the drill and blast process. It is one that is often overlooked in the mining industry in many operations due to many factors such as lack of skilled personnel, or a lack of required resources. The data obtained from near field blast vibration monitoring can be used to provide additional feedback into blast reviews and help in any drill and blast optimisation projects. This paper highlights key aspects of underground drill and blast reviews and the use of near field blast vibration monitoring for post blast analysis and shares learnings from various projects that the authors have been involved in within Australia and abroad.

Mar 29, 2023

By M Haest, O Dominguez, D Mittrup

With the current focus in the mining industry on reducing costs, while simultaneously improving ore quality, infrared spectroscopy is a tool that can potentially assist companies to meet both challenges. Changes in the nature of infrared spectra are strongly influenced by changes in mineralogy, which is a key input variable for exploration (geology and orebody modelling and ore characterisation) and mining (pit design, mine scheduling and processing plant design/management).Infrared spectroscopic logging of drill holes has been embedded as a standard tool in BHP Billiton Iron Ore exploration, with a process set up to automatically deliver mineralogy and associated imagery to the end users (typically exploration geologists). The availability of consistent and automated mineralogy drill hole logs across a project is improving the output quality and reducing re-work.BHP Billiton Iron Ore is now looking into using the same infrared spectroscopic data for other applications, including improving predictions of geometallurgical and geotechnical parameters. Trials show that addition of infrared spectroscopic data to conventional data sets (element analysis and depth information) is significantly improving the accuracy of regression models to predict the lump-fine ratio.Further initiatives around infrared spectroscopic data in BHP Billiton Iron Ore include the installation of infrared spectroscopic sensors over conveyor belts, infrared spectroscopic mine face scanning and infrared spectroscopic blasthole logging. The ultimate vision is to have consistent, seamless mineralogical data from infrared spectroscopic sensing available throughout the mineral value chain (exploration/mining/processing). This seamless infrared spectroscopic data ‘bridge’ will allow the transfer of knowledge between the different sections of the value chain (exploration, mining and processing). For example, ore handle-ability could be predicted on exploration samples using regression models built from processing plant observations. In the opposite direction, information gathered about the buried stratigraphy by infrared spectroscopy utilised during exploration, could be used to predict the stratigraphy encountered during mining. This collaboration across BHP Billiton Iron Ore is expected to deliver significant savings, while improving the quality of the final product, thus helping to drive efficiency over the next decade.CITATION:Haest, M, Mittrup, D and Dominguez, O, 2015. Reaping the first fruits – infrared spectroscopy: the new standard tool in BHP Billiton Iron Ore Exploration, in Proceedings Iron Ore 2015, pp 277–284 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By N Cusworth, W R. Mackenzie

"In 2007, the authors presented a framework for the conduct of resource project feasibility studies and provided guidance on minimum standards and best practice (Mackenzie and Cusworth, 2007).This paper will present the authors’ observations in relation to feasibility studies undertaken to support investments made during the unprecedented period of resource project capital investment since 2007. It will also provide comments on general trends in the mining industry’s approach to project assessment and update recommendations on best practice.CITATION:Mackenzie, W R and Cusworth, N, 2016. The use and abuse of feasibility studies – has anything changed?, in Proceedings Project Evaluation 2016, pp 133–148 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 8, 2016

By M J. Noy

The automated measurement of rock fragmentation particle size distribution in the muck during muck excavation has been developing over the last 16 years. The introduction of stereo camera imaging of the muck has provided improved automated particle segmentation for image-based measurement algorithms. Recently, a new vision system processing algorithm has been developed. The inclusion of 2D texture in the analysis has provided a significant improvement in the definition of the finer size fractions, which has resulted in the automated analysis no longer requiring calibration.The previous stereo vision system algorithm required analysis calibration to account for poor ‘small particle’ definition in the 3D surface profile. This was because of the depth perception limitations of the stereo camera system at greater than 8 m. The new algorithm has been implemented on a number of shovel-installed vision systems, and the algorithm’s performance in automated analysis has been assessed against a diligent manual analysis of the same fragmentation images. The new algorithm provides improved distribution resolution and accuracy.CITATION:Noy, M J, 2015. Evaluation of a new vision system algorithm for automated fragmentation measurement from a shovel, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 721–726 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

The revival of the mining industry at Captain's Flat after a long period of years of inactivity has attracted attention to the importance of the ore-deposits of that field as potential sources of supply of lead and zinc. Mindful of the necessity for taking stock of the State's mineral resources, the Department of Mines of New South Wales as part of its programme of geological investigation, carried out a survey of the oredeposits and associated country rocks during 1938 and 1940.Surface geology was mapped in detail and all available exposures were examined and logged. Unfortunately, and this condition militates against the formulation of conclusions because of insufficiem.t data, some of the older workings, notably in Keating's Section, were inaccessible and the logging of levels and stopes is by no means as complete as could be desired. However, with the progress of development and exploration, further information of geological value will come to hand for incorporation in supplementary reports. It may be expected that, under such circumstances, modification of certain statements herein expressed may be necessary but it is not anticipated that any vital alteration will be occasioned.Within the State of, New South Wales, Captain's Flat ranks second to Broken Hill as a pqtem.tial producer of lead and zinc. In addition, large quantities of iron pyrites are available for the manufacture of sulphuric acid which finds application in the superphosphate industry.The mines are now controlled by an operating company known as Lake George Mines, Ltd., incorporated in New South Wales, the parent organisation being the Lake George Mining Gorporation Ltd., registered in London.Over £600,000 has been spent by the Company in exploration, mine development, surface plant, housing and water 'conservation, while the State' Government constructed a branch railway from Bungendore at a cost of £200,000. The various activities consequent upon these development and construction programmes and the prospect of employment in the industry has led to a rapid increase in the population of the township.The State, generally, has benefited to the extent of a substantial contribution to the relief of the unemployment problem, and it is hoped that reasonable permanency will be assured to some hundreds of workers for many years.

Jan 1, 1941

By H Weitz

Bateman Engineering provided process technology and engineering design to China Yunnan Metallurgical Company (CYMCO) for a 30 MW DC furnace for the production of high-grade titanium dioxide slag.Following the successful commissioning of the furnace during the latter part of 2009 and the first quarter of 2010, a period of adverse circumstances resulted in having to operate the furnace without feed and at a low power input for a period of time. When normal feed resumed, a layer of solid material was detected on the slag-iron interface during sounding measurements. The condition of the iron was also significantly altered. The iron temperature was much higher than the design value, but the carbon content had decreased to such an extent that a large amount of iron solidified in the furnace, which made iron tapping very challenging. The slag temperature was increased in order to melt the solidified iron. However, severe sidewall damage resulted, which finally led to a burn-through. A number of samples were taken from the slag that remained in the furnace. These samples were analysed to determine the chemistry and phase profile throughout the slag bath. The mechanisms of formation of the high melting-temperature phase on the slag-iron interface are discussed, as well as procedures that can be applied to prevent a recurrence of this phenomenon. Some recommendations are made for instances when furnace feeding is interrupted for an indeterminate period.

Oct 5, 2011

Alfred Nobel first invented a practical detonator in 1863 and then the blasting cap in 1865. At that time the detonator was used on the end of a length of safety fuse to initiate nitroglycerine-based explosives. Since then the detonator has gone through a number of changes. The instantaneous electric detonator was the first to allow remote firing. The electric delay detonator followed and allowed for timing between holes. In the mid 1970s the NONEL« Tube was invented. This tube combined with NONEL« detonators meant that many of the safety issues, such as stray current and radio frequency, associated with electric delay detonators were eliminated. This system gave the mining industry a reliable and fairly accurate system with which to detonate shots of any size. Since the early 1980s a large amount of research and development work has been done around the world to create a more accurate detonator for the mining and quarrying industry. After years of research, electronic detonators have emerged as the most accurate and precise initiation system available to the mining and quarry industry today. Electronics provide the user with millisecond timing accuracy. The improved level of timing control allows operations to improve fragmentation, throw and reduce vibration levels. There are now a number of different electronic detonator suppliers on the market today. In 2004 Dyno Nobel formed a joint venture called DetNet with AECI. DetNet has a suite of electronic detonators: DigiDet«, HotShot« and QuickShot«. This paper will focus on the HotShot« system, the first of the three new initiation systems to be released to the market in Australia by Dyno Nobel.

Jan 1, 2005

By R Justa Cámara, L M. Pinillos Lorenzana

Barcelona Metro Line 9 (Line 9) is an essential infrastructure, improving the transversal transport in Barcelona by connecting the greater part of the currently existing radial lines. The purpose of Line 9 is to create a peripheral line surrounding the city of 1.6 million people (metropolitan area exceeds five million), and includes 52 stations, of which a total of 32 are deep shafts and 19 transfer stations in a densely populated area with several geographical constraints.The tunnel has an inner diameter of 10.90 m, bored with an earth pressure balance (EPB) tunnel boring machine (TBM) in soil sections with precast concrete lining type universal ring and segments 40 cm thick.A single tunnel solution was adopted, driven by functionality and costs savings. The internal tunnel section is divided into two levels to allow for one way rail transit including the platforms in each station on each level in order to optimise the space created by the TBM excavation and comply with the operational needs. The division in two areas of the tunnel was carried out through the construction of a horizontal slab resting on the tunnel segments with a constant thickness of 40 cm at the central part of the slab and supporting side walls.CITATION:Justa Cámara, R and Pinillos Lorenzana, L M, 2014. Two transit levels in one tunnel tube – an innovation in Barcelona Metro Line 9, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 387–398 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By F Shi, W Huang, D Seaman, K Runge

High Voltage Pulse (HVP) technology is a novel process that could potentially be the step-change needed in ore processability in the mining industry. The propensity of high voltage pulses towards mineral-enriched ore particles during treatment makes this technology selective and has the potential to enable ore pre-concentration by size separation. In this study, the potential for pre-concentration of a low grade copper-gold ore sample subjected to HVP pretreatment is investigated and compared to that achievable after mechanical breakage in JKMRC’s rotary breakage tester (JKRBT). The data show that a better pre-concentration result can be achieved after HVP processing than conventional breakage. The gold pre-concentration potential is much better than that observed for copper. 4D HVP pre-concentration characteristic curves were produced to assess the metallurgical performance possible as a function of energy input. The case study shows that when targeting a nominal metal recovery of 90 per cent for gold, the HVP pre-concentration technique can split the low grade ore (0.9 ppm gold and 0.28 per cent copper in the feed size 26.5-37.5 mm) into two components – a low grade oversize material (0.3 ppm gold and 0.15 per cent copper) and a high grade undersize material (1.0 ppm gold and 0.3 per cent copper). The mass split to the low grade is 23 per cent. Under this mass split scenario, gold recovery to screen undersize is 90 per cent and copper recovery is 85 per cent. The HVP treatment of this feed size requires a specific energy (spark) of 2.8 kWh/t.There is further research that would be required before industrial uptake of the HVP pre-concentration technology would be possible. This paper also outlines the research challenges that need to be overcome.CITATION:Huang, W, Shi, F, Antonio, C, Runge, K and Seaman, D, 2018. High-voltage pulse pre-concentration study using a low-grade copper-gold ore, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 327–338 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By N Haque, S Northey

Water in mining, mineral processing and metal production on a life cycle basis has been at the top of agendas for various industries, government agencies, research organisations, academic institutions and communities. As a result, a number of water footprint assessment methodologies have been developed. However, their practical applications in mining and mineral processing industries with specific case studies are still rare.A key objective of the Minerals Down Under Flagship is to contribute to the long-term sustainability of the Australian mining and mineral industries. Researchers in the Mineral Futures theme have developed robust assessment methods to evaluate the impact of mining and minerals technology development on the environment. The future of mining and the mineral industry is strongly linked with its sustainability - better water management strategies will need to be implemented.Life cycle assessment (LCA) has been a recognised method for measuring the environmental impacts of products, processes and services. It provides a scientifically sound method of comparing products and processes using a common basis and identifies so called æhot spotsÆ and opportunities for reducing environmental impacts. The water footprint of mining, mineral processing and metal production using an LCA basis is still scarce in the literature. Research methodology is now being applied in detail for copper, gold and nickel. A primary focus has been the relationship between ore grade and water use for which mathematical models are being developed. These types of models provide inputs for LCA of mining and mineral processing plants and can identify water saving opportunities through scenarios and process route analysis.CITATION:Northey, S and Haque, N, 2013. Life cycle based water footprints of selected mineral and metal processing routes, in Proceedings Water in Mining 2013 , pp 35-50 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 26, 2013

By Ovchinnikov YN, Novikov VS, Spirin NA, Babushkin NM, Mysik AF, Shcherbatskii VB, Kukarkin AS

Laboratory investigations were carried out to determine the resistance coefficient of the flow through beds irrigated with wetting and non-wetting liquids. A formula was obtained which may be used to evaluate the resistance of the irrigated packing. Quantitative investigations were also carried out on operating furnaces at Magnitogorsk. Continuous measurements of the lower pressure drops were made under different furnace conditions. Pressures were measured in the tuyere space and the bosh region. A significant transient behaviour of the pressure drop was observed in the irrigated zone as a function of the accumulation of the liquid phase in the bosh region as smelting progressed. Additionally, transient processes were also investigated in the upper furnace zones. The basic cause of the transient behaviour was shown to be the irregularity of burden descent caused by the casting cycle. It was shown that the rate of burden descent between consecutive casts reflects fairly accurately the accumulation and drainage of the liquid products as a result of which heat transfer, reduction and aerodynamic processes assume transient character. In practically all cases of casting a decrease in blast pressure and that over the furnace height of 0.2 kg/cm2 was observed. The analyses of radial gas composition at the stock line showed that compositional variations connected with the casting cycle are most pronounced in the central and peripheral regions, whilst in the intermediate regions the conditions are relatively stable. Calculations show that as casting progresses there is a decrease in the gas flow rate at the periphery and an increase in the centre of the furnace. The transient nature of the aerodynamic processes in packings revealed the existence of an appreciable reserve capacity. Elimination of transience was tested on the furnace at Magnitogorsk and improved operating and economical furnace parameters obtained.

Jan 1, 1975

By J Safarian, D Hariswijaya

Treating bauxite residue as an alternative source of metals for iron and aluminium industry is an approach to promote circular economy in metal industries. Reduction of metal oxides with H2-based process is an important step on decarbonisation of metal industry. In this study bauxite residue pellets were prepared and were reduced with different H2-H2O gas compositions at different temperatures which yielded with various degrees of reduction. The bauxite residue pellets were made from a mixture of bauxite residue and Ca(OH)2 powders and sintered at 1150°C. Hydrogen reduction was carried out on the oxide pellets using a resistance furnace at elevated temperatures in controlled reduction atmosphere of H2-H2O gas mixtures which resulted in reduction of iron oxides in the pellets. Unreduced and reduced pellets were subsequently heated to 1400°C to study their smelting behaviour using differential thermal analysis (DTA) and thermogravimetric analysis (TGA) technique to investigate the evolution of phases related to slag formation via smelting. Equilibrium module of Factsage™ ver 8.1 was utilised to analyse results of thermal analysis. It was observed that Tricalcium phosphate-β (CaP2O8), Bredigite (Ca7Si4MgO16), Rankinite (Ca3Si2O7), and calcium alumino ferrite (Ca[Al,Fe]6O10) were formed during thermal analysis as intermediate phases. The initial slag formation for sintered and reduced pellets occurred at 900°C which mainly contains calcium and small amount of strontium component. The slag formation rate increases significantly starting from 1100°C when iron oxides started to form initial molten slag phase which then followed by other oxides dissolution in the system. Gas formation was observed at 1180°C and it was found that the gas to be released from unreduced pellets is O2 meanwhile the gas to be released from reduced pellets is SO2 gas. Gas formation rate for both pellets start to increase at 1280°C when the remaining chemically bonded gas start to be released from the system.

Jun 19, 2024