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Mayfield West, Australia

Strezov V.,Macquarie University | Evans T.J.,Hamersley Iron Pty Ltd | Zymla V.,Ecole Centrale Paris | Strezov L.,Crucible Group
International Journal of Mineral Processing | Year: 2011

Degradation of iron ore particles during ironmaking produces airborne particulate matter and reduces process efficiency. The work presented here investigates thermal deterioration of iron ore particles during thermal processing of two types of iron ores, goethite and hematite. While the hematite iron ore showed close to an inert thermal behaviour, the goethite sample exhibited significant structural and thermochemical changes during heating at approximately 300 °C due to the breakdown of the hydroxyl bonds and release of water vapour. The associated strain in the particle caused by structural deterioration and crack propagation through the iron ore particle during heating was further modelled in this work. The model showed that cracks are initiated on the surface of the goethitic particle with crack propagation from the surface down to 20% of the particle diameter. Heating of iron ore particles in a fixed bed reactor did not produce particle fragmentation, however the structural changes during heating of the goethitic iron ore sample were so significant that the heating is expected to destabilise the particle structure and generate conditions favourable for particle degradation through mechanical or reduction induced particle deterioration. © 2011 Elsevier B.V. All rights reserved.

Mukunthan K.,Deakin University | Mukunthan K.,Crucible Group | Hodgson P.D.,Deakin University | Strezov L.,Deakin University | Stanford N.,Crucible Group
ISIJ International | Year: 2013

The castability and microstructures produced from strip casting simulations of three compositions in the 200 series stainless steels have been examined. The nucleation density was similar for all three compositions. The as-cast microstructure showed very fine austenite grains of 10-20 μm in width. Retained delta ferrite was observed in the inter-dendritic regions, and was likely to be stabilised by the segregation of Cr into these regions. An analysis of the crystallography expected of different solidification sequences is presented, but a strict adherence to the Kurdjumov-Sachs orientation relationship was not found in these samples. © 2013 ISIJ.

Mukunthan K.,Deakin University | Mukunthan K.,Crucible Group | Hodgson P.D.,Deakin University | Sellamuthu P.,Deakin University | And 3 more authors.
ISIJ International | Year: 2013

A strip casting simulation of the iron-based specialty alloy known as Fecral (or Kanthal) has been carried out. The alloys tested were found to be easily castable and show good surface quality. Increasing the melt superheat increased the nucleation density and heat flux, leading to a refined ferrite grain size. Although changing the gas atmosphere during casting was observed to modify the measured heat flux, this did not correlate to any change in the nucleation density. The cast strips were able to be rolled without cracking, and showed mechanical properties similar to those found in comparable alloys after conventional thermo-mechanical processing. © 2013 ISIJ.

Mulligan C.J.,Macquarie University | Mulligan C.J.,Crucible Group | Strezov L.,Crucible Group | Strezov V.,Macquarie University
Energy and Fuels | Year: 2010

The pyrolysis behavior of wheat straw and mallee residue and resulting gases, liquids, and chars were examined. The specific heat and thermal conductivity of both species were measured using computer-aided thermal analysis at heating rates of 10 and 100 °C/min to a temperature of 1000 °C. The sample decomposition was also measured by thermogravimetry. Gas chromatography detected evolved gases, and the bio-oils were characterized using GC-MS. Chars were examined using FTIR, proximate, and ultimate analysis. Both species initially displayed endothermic behavior, followed by rapid decomposition and fluctuating specific heat and thermal conductivity between 250 and 500 °C. Oxides of carbon were theprimary gases evolved, with small amounts of hydrocarbons and hydrogen. The bio-oils predominantly contained oxygenated aromatics and organic acids, and the chars had high fixed carbon and low sulfur. In all instances approximately half of the product output was liquid. Straw produced 14% gas and 32% solid at 500 °C, whereas mallee produced 13% gas and 36% solid. At 1000 °C the proportions of solid decreased and gas increased. The efficiency of pyrolysis to 500 °C, assuming no losses, was around 96% for both species. At 1000 °C the efficiency decreased, with pyrolysis of mallee slightly more efficient than for straw. © 2009 American Chemical Society.

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