ORALS

SESSION: IronTuePM1-R3	Poveromo International Symposium (8th Intl. Symp. on Advanced Sustainable Iron & Steel Making)
Tue. 29 Nov. 2022 / Room: Arcadia 1
Session Chairs: Tateo Usui; Session Monitor: TBA

14:50: [IronTuePM107] OS
Relating Physical and Metallurgical Properties of Kumba Lump Ore to the behaviour in processes
Kobus Vreugdenburg¹ ; Jacques Muller¹ ; ¹Anglo American, Pretoria, South Africa;
Paper Id: 74 [Abstract]

<p>The standard physical and metallurgical tests are designed to differentiate between iron bearing materials. The standard tests prescribe the equipment and test conditions to compare test results across laboratories. Standard tests are widely accepted and used by suppliers and consumers of the materials for commercial purposes and process control. The conditions in blast furnaces and direct reduction processes are dynamic while the standard tests subject the iron bearing material to fixed conditions, making it difficult to relate the impact of standard properties on process performance. [1]<br />The ISO 3271 standard specifies a method for evaluating the resistance of iron ores to size degradation by impact and abrasion. ISO 3271 prescribes 200 revolutions in a tumble drum to obtain the tumble index (TI), the size degradation Kumba Lump ore from load port to discharge port was correlated with the number of revolutions needed in the ISO tumble drum to obtain similar degradation.<br />ISO 4696 and ISO 11257 standards are used to evaluate the degree of size degradation of iron ores due to low temperature reduction-disintegration in blast furnaces and direct reduction processes respectively. The use of isothermal reduction does not reflect the dynamic conditions in the processes and the reduction disintegration index (RDI) does not always reflect the actual size degradation [1][2]. The ISO tests are done on one size fraction, and the reduction disintegration size fractions experience are different. The effect of test temperature and size fraction on reduction disintegration were evaluated. <br />ISO 4695 and ISO 7215 standards are used to evaluate the relative reducibility of iron ores under blast furnace conditions. The standard tests are done on the 10 to 12.5 mm size fraction or on the 18 to 20mm size fraction, depending on which of the two ISO standards are used. The result is expressed as the reducibility index (RI). The rate at which oxygen can be removed from the ore is dependent on the available surface area - coarser particles will be reduced at a lower rate than finer particles. The actual size fraction of the lump ores used in the blast furnace is around 6.3 to 40mm, the mean reducibility of the lump ore considering the particle size distribution were investigated. <br />The relevance of physical and metallurgical properties of Kumba Lump Ore on the performance in practice were investigated.</p>

References:
<p>[1] C.E. Loo, N.J. Bristow, Properties of iron bearing materials under simulated blast furnace indirect reduction conditions Part 1 Review and experimental procedure, Ironmaking &amp; Steelmaking 25(3):222-232 (January 1998)\n[2] C.E. Loo, N.J. Bristow, Properties of iron bearing materials under simulated blast furnace indirect reduction conditions Part 2 Reduction Degradation, Ironmaking &amp; Steelmaking 25(4):287-295 (January 1998)</p>

SESSION: IronTuePM1-R3	Poveromo International Symposium (8th Intl. Symp. on Advanced Sustainable Iron & Steel Making)
Tue. 29 Nov. 2022 / Room: Arcadia 1
Session Chairs: Tateo Usui; Session Monitor: TBA

15:15: [IronTuePM108] OS
Evaluating Kumba Lump Ore Performance in a Blast Furnace Burden
Jacques Muller¹ ; Kobus Vreugdenburg¹ ; ¹Anglo American, Pretoria, South Africa;
Paper Id: 73 [Abstract]

<p>The blast furnace operation and economics are significantly influenced by the performance of burden materials descending in the furnace shaft. Changes in burden permeability and reducibility relates to the degree of indirect reduction, and therefore reductant requirement and iron productivity. Chemical composition, and physical and metallurgical properties of burden materials are determined using standard (ISO) test procedures. Tests are performed on specific material size distributions, and mostly at constant temperatures and gas compositions representative of typical blast furnace zones. <br />Materials are directly compared on qualities derived from standard tests. However, the marginal impacts on economic and emissions performance when substituting burden materials are not easily determined from standard material qualities. Contributing to inaccuracies are the transient nature of temperature and gas composition in actual processes, differences in material size distribution, and effects of other material properties.<br />The softening, melting, and dripping behaviour of materials at transient conditions, typical for blast furnaces, are determined in high-temperature tests [1]. In this investigation, such tests are performed on iron ore sinters, pellets, and lump ores using the test procedure developed by Ritz et al. 1998 [2]. A material sample, normally -12.5+10 mm, is placed under load and electrically heated while varying gas mixtures are injected over time to resemble the changing conditions down the blast furnace shaft.<br />Sample temperature, pressure drop, compaction, and the outlet gas composition are continuously measured during tests. Results derived include the location of the expected softening and melting points in the blast furnace in terms of temperature and time (i.e. location and thickness of the cohesive zone), and the degree of reduction over time. These tests are believed to more accurately indicate the amount of indirect reduction to be expected in the blast furnace and therefore the impact on the reductant requirement when comparing burden materials.<br />In this work, the material qualities determined in standard (ISO) tests were related to the actual performance in the blast furnace derived from high-temperature tests by using reaction kinetics and thermodynamic modelling. The purpose of this being to more accurately estimate blast furnace performance from more readily available burden material qualities. <br />Aspects investigated include: (1) softening and melting behaviour in relation to the degree of reduction and chemical composition during processing, (2) the amount of indirect reduction achieved at the softening point (start of cohesive zone) relative to a reducibility index value for a material with size distribution of interest, and (3) the impact that percentages of different materials in the burden has on the overall blast furnace performance.</p>

References:
<p>[1] X. Liu, T. Honeyands, G. Evans, P. Zulli, D. O'Dea, Ironmaking &amp; Steelmaking April (2018) 1-15.\n[2] V.J. Ritz, H.A. Kortman, 2nd International Congress on the Science and Technology of Ironmaking and 57th Ironmaking Conference (1998).</p>