March/April 2015

CIM Journal & CIM Metallurgical Quarterly

Excerpts taken from abstracts in CIM Journal, Vol. 6, No. 1.
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Co-extraction of coal and methane

H. Guo, Commonwealth Scientific and Industrial Research Organisation (CSIRO), Brisbane, Queensland, Australia; L. Yuan, Huainan Mining Group Co. Ltd., Huainan, Anhui, China; Y. P. Liang, Q. D. Qu, J. Qin, S. Xue, and J. Xie, Commonwealth Scientific and Industrial Research Organisation (CSIRO), Brisbane, Queensland, Australia

ABSTRACT This paper presents key outcomes of a major Asia-Pacific Partnership project between the Commonwealth Scientific and Industrial Research Organisation and Huainan Mining Industry Group Co. Ltd. to develop and demonstrate advanced technologies at Pansan mine, Huainan, China. A comprehensive approach assessed fundamental strata and coal seam methane conditions during mining and optimized mining sequences and coal mine methane capture systems. The project demonstrated a practical approach and procedures for advanced coal and methane co-extraction systems, improved mining safety and efficiency, increased methane capture and use, and reduced fugitive methane emissions.


History of electrolytic cobalt refining at Vale Canada (Inco)

B. R. Conard, BRConard Consulting Inc., Oakville, Ontario, Canada

ABSTRACT Cobalt refining at Vale Canada (previously known as Inco) has been associated with Ni production. Because certain compounds of both metals carry risks for adverse health endpoints by inhalation exposure, it is critical to understand the aerosol concentrations of specific substances and the metallurgical processes through which they enter the air. Vale Canada has therefore decided to describe the histories of its Ni-related operations and to report industrial hygiene measurements when available. This paper describes electrolytic Co operations carried out at Port Colborne, Ontario (1954– 1966), and provides aerosol measurements (1995–2008) for current Co electrowinning operations.


Prospects for renewable energy systems in the mining industry

B. Fleet, Ryerson University and Fleetec Inc., Toronto, Ontario, Canada; A. Davidse, Deloitte Inc., Toronto, Ontario, Canada; R. DasGupta and S. Hon, Electrovaya Corp., Mississauga, Ontario, Canada; J. Li, A. Pringle, and C. Searcy, Ryerson University, Toronto, Ontario, Canada

ABSTRACT The mining industry is facing serious long- and short-term challenges relating to uncertain commodity prices, environmental pressures, and margin compression due to rising energy costs. Energy issues, formerly treated as an operating cost, are changing as executives search for longer term solutions to deal with uncertain fossil fuel prices and greenhouse gas emissions. Consequently, mining executives are increasingly willing to consider introducing a proportion of renewable energy (RE) systems into the mine energy mix. This paper examines how RE can be successfully integrated at mine sites, as well as some of the benefits and barriers to their wider adoption.

Canadian Metallurgical Quarterly cover
Excerpts taken from abstracts in CMQ, Vol. 53, No. 1.
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Freeze lining formation in continuous converting calcium ferrite slags – I

J. Jansson, P. Taskinen, and M. Kaskiala, School of Chemical Technology, Aalto University, Esbo, Finland

ABSTRACT The initial freeze-lining growth rate in calcium ferrite slags at copper saturation is high and comparable to iron silicate slags. The entire freeze-lining layer is crystalline, from the cold end to its hot-face in contact with the molten slag. Industrial copper converting slags from a continuous flash converting furnace, processing solid high-grade matte to blister copper, generate a thin calcium sulphate bonding layer against the water-cooled metal surface during the very first minutes of the slag-to-cooling element contact. The rare solidification behaviour was observed using the water-cooled probe technique in rotating MgO crucibles, at slag temperatures of 1,325 °C when liquidus temperature of the flash converting slag was estimated to locate at about 1,245 °C. The body of the freeze lining is mostly composed of magnetite, various mixed calcium– copper ferrites and delafossite embedded in an intergranular phase of metallic copper and some copper oxide. The arsenic oxides dissolved in the slag are precipitated as solid calcium arsenates in the freeze lining.


Freeze lining formation in continuous converting calcium ferrite slags – II

J. Jansson, P. Taskinen, and M. Kaskiala, School of Chemical Technology, Aalto University, Esbo, Finland

ABSTRACT The heat transfer properties of freeze linings generated in laboratory conditions, by industrial calcium ferrite slags from a continuous copper matte flash converting furnace, have been studied in situ in the molten slag using a water cooled probe technique. The measured heat conductivity of the freeze lining formed, estimated from direct measurements in steady state conditions, was 8.0±1.5 W m−1 K−1. The obtained heat conductivity of the freeze lining is 50–100% higher than that of the iron silicate slag freeze linings. The calcium ferrite slag forms a fully crystalline freeze lining. Various ferrites and metallic copper develop the observed high heat conductivity when copper precipitated from the slag during solidification fills the intergranular cavities of the ferrite crystals tightly in forming the freeze lining layer.


Kinetic analysis of silicothermic process under flowing argon atmosphere

W. Wulandari, G. A. Brooks, M. A. Rhamdhani, Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, Hawthorn, Victoria, Australia; and B.J. Monaghan, School of Mechanical Materials and Mechatronics Engineering and Blue Scope Steel Metallurgy Centre, University of Wollongong, Wollongong, New South Wales, Australia

ABSTRACT The Pidgeon process, a silicothermic reduction of calcined dolomite under vacuum, is the dominant process to make magnesium metal. Experimental data from Morsi et al. were utilised for kinetics analysis of silicothermic reduction of calcined dolomite under argon atmosphere. A number of kinetic models were assessed to evaluate the rate-controlling step in the process. The results suggest that the reaction is controlled by the solidstate diffusion of reactants with the Jander and Ginstling–Brounshtein model providing the best representation of the process kinetics. Mass transfer effects of magnesium vapour from the surface to the bulk gas phase was also analysed. These results suggest that gas–film mass transfer is not the limiting step of the kinetics. Pore diffusion through briquettes is postulated to have some effect on the kinetics but solid-state diffusion is the major ratelimiting step.


Reducibility of nickeliferous limonitic laterite ore from Central Anatolia

S. Pournaderi, Department of Metallurgical and Materials Engineering, Middle East Technical University, Ankara, Turkey; E. Keskinkılıç, Department of Metallurgical and Materials Engineering, Atılım University, Incek, Ankara, Turkey; A. Geveci and Y. A. Topkaya, Department of Metallurgical and Materials Engineering, Middle East Technical University, Ankara, Turkey

ABSTRACT Limonitic nickel laterite from Sivrihisar reserve in Turkey was reduced at 700–1,100 °C by the addition of 5.74, 8.61 and 11.48 wt-% coal under an argon atmosphere. The run-of-mine ore and the reduced samples were studied using X-ray diffraction. The metallisation of Fe was found to be limited up to 900 °C, but increased rapidly at higher temperatures. The metallisation of Ni and Co increased when the temperature was increased from 700 to 800 °C, almost leveled off up to 900 °C and then increased up to 1,100 °C. The results also showed that increased coal additions did not affect Fe metallisation up to 900 °C. At 1,000 °C the metallisation of Fe became slightly better, but its effect was more pronounced at 1,100 °C. The increased coal addition affected the nickel reduction equally at all temperatures, while it had no effect on the metallisation of Co.


Diffusion induced isothermal solidification during transient liquid phase bonding of cast IN718 superalloy

M. Pouranvari, A. Ekrami, and A. H. Kokabi, Department of Materials Science and Engineering, Sharif University of Technology, Tehran, Iran

ABSTRACT In transient liquid phase (TLP) bonding for commercial applications, one of the important key parameters is the holding time required for complete isothermal solidification tIS, which is a prerequisite for obtaining a proper bond microstructure. The objective of the study is to analyse the isothermal solidification kinetics during TLP bonding of cast IN718 nickel based superalloy. Experiments for TLP bonding were carried out using a Ni–7Cr–4.5Si–3Fe–3.2B (wt-%) amorphous interlayer at several bonding temperatures (1,273–1,373 K). The time required to obtain TLP joints free from centreline eutectic microconstituents was experimentally determined. Considering the solidification behaviour of residual liquid, tIS could be predicted by a mathematical solution of the time dependent diffusion equation based on Fick’s second law.


Estimation of porosity and shrinkage in a cast eutectic Al–Si alloy

S. Samavedam, MGIT, Hyderabad, India; S. B. Sakri, DRDL, Hyderabad, India; D. Hanumantha Rao, MVSR Engineering College, Hyderabad, India; and S. Sundarrajan, National Institute of Technology, Trichy, India

ABSTRACT Estimation of volume deficit of US 413 cast aluminium alloy has been discussed in the present study. Decrease in specific volume leads to volume deficits in castings and it can be envisaged as a casting defect. Hence, information about volume deficit and its distribution is essential in minimising casting defects. The volume deficit of a given casting is the combination of macro cavities, internal porosity, surface sinks and volumetric contraction. These defects are measured using mathematical formulae. Estimation of internal closed porosity has been addressed through X-ray computer tomography. Influence of pouring temperature on the volume deficit characteristics has been studied.


Evolution of primary α-Al particles during isothermal transformation of rheocast semi solid metal billets of A356 Al–Si alloy

O. Lashkari, Bekaert Canada Limited, Surrey, British Columbia, Canada; and R. Ghomashchi, School of Mechanical Engineering, University of Adelaide, Adelaide, South Australia, Australia

ABSTRACT Semi solid metal (SSM) processing is a relatively new technology for metal forming, different from the conventional metal shaping technologies that use either solid or liquid metals as the starting material. Semi solid metal processing deals with semi solid slurries, in which non-dendritic solid particles are dispersed in a liquid matrix. The solid volume fraction could vary between 0.1–0.5 with apparent viscosity close to that of liquid state. The slurry flows easily under pressure and makes complicated shapes with high degree of die filling and integrity. There are different ways to prepare SSM slurries including the application of direct or indirect mechanical stirring, chemical treatments of the melt, and manipulation of pouring temperature. One of the important parameters controlling the mechanical and flow characteristics of SSM billets is the morphology of the primary solid phase, e.g. α-Al for Al–Si alloys. The morphological evolution of primary α-Al particles of SSM processed A356 Al–Si billets is studied with variant soaking times, 0–480 s, at 595°C, i.e. 0.33 fraction solid before the applied compression force. The effect of applied compression force of 33 kgf on the evolution of dendritic morphology was also investigated at the same temperature and within the same holding time range. The microstructure was characterised quantitatively and showed that spheroidisation and coarsening are active during the course of treatment with the application of compressive forces bringing about further refinement.


The influence of alkaline salt bath quenching on the microstructure and mechanical properties of AISI D2 steel

A. Malekan, A. Pedram, Sh. Raygan, J. Rassizadeh Ghani, School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Tehran, Iran; and M. Malekan, Department of Mechanical Engineering, Shahid Rajaee Teacher Training University, Lavizan, Tehran, Iran

ABSTRACT In this work, the microstructure and mechanical properties of AISI D2 tool steel is compared after air cooling and quenching in alkaline salt bath (60% KOH and 40% NaOH). The results have shown that the hardness of the samples quenched in alkaline salt bath with different temperatures followed by tempering at 540 °C was higher than the hardness of air cooled sample. The maximum hardness from surface to centre of the samples was achieved after quenching in salt bath at 220 °C. The microstructure and consequently the mechanical properties were altered after quenching in different media. It is also shown that hardening of D2 steel in alkaline salt bath can result in higher strength values than air cooling while there was no significant change in the impact energy of the samples.

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