Degradation of Iron Oxide Caused by Alumina during Reduction from Magnetite
The degradation mechanism of iron oxides caused by alumina during reduction from magnetite has been studied. The experiments were carried out by reducing briquettes containing various mixtures of commercial magnetite fines and Al2O3 in a CO/CO2 atmosphere at 950°C in thermo-gravimetric equipment. Fo...
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| Veröffentlicht in: | ISIJ International 2003/05/15, Vol.43(5), pp.597-605 |
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| creator | Paananen, Timo Heinänen, Kyösti Härkki, Jouko |
| description | The degradation mechanism of iron oxides caused by alumina during reduction from magnetite has been studied. The experiments were carried out by reducing briquettes containing various mixtures of commercial magnetite fines and Al2O3 in a CO/CO2 atmosphere at 950°C in thermo-gravimetric equipment. Following reduction, samples were examined using optical microscopy, SEM-EDS and XRD. The diffusion of Al cations into the magnetite during reduction induces swelling and cracking of the briquettes. The composition of the magnetite phase approaches the composition of hercynite during reduction. Assuming the spinel structure is that of hercynite, reduction to non-stoichiometric wüstite (Fe0.88O) causes an expansion of over 16%. This transformation causes high tension forces in the magnetite/hercynite phase in the vicinity of the interface with the wüstite which presumably account for the breakdown of the structure during the reduction. |
| doi_str_mv | 10.2355/isijinternational.43.597 |
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The experiments were carried out by reducing briquettes containing various mixtures of commercial magnetite fines and Al2O3 in a CO/CO2 atmosphere at 950°C in thermo-gravimetric equipment. Following reduction, samples were examined using optical microscopy, SEM-EDS and XRD. The diffusion of Al cations into the magnetite during reduction induces swelling and cracking of the briquettes. The composition of the magnetite phase approaches the composition of hercynite during reduction. Assuming the spinel structure is that of hercynite, reduction to non-stoichiometric wüstite (Fe0.88O) causes an expansion of over 16%. This transformation causes high tension forces in the magnetite/hercynite phase in the vicinity of the interface with the wüstite which presumably account for the breakdown of the structure during the reduction.</description><identifier>ISSN: 0915-1559</identifier><identifier>EISSN: 1347-5460</identifier><identifier>DOI: 10.2355/isijinternational.43.597</identifier><language>eng</language><publisher>Tokyo: The Iron and Steel Institute of Japan</publisher><subject>alumina ; Applied sciences ; degradation ; degradation mechanism ; Direct reduction ; Exact sciences and technology ; hercynite ; Iron and steel making ; magnetite ; Metals. Metallurgy ; Production of metals ; reduction ; wüstite</subject><ispartof>ISIJ International, 2003/05/15, Vol.43(5), pp.597-605</ispartof><rights>The Iron and Steel Institute of Japan</rights><rights>2003 INIST-CNRS</rights><lds50>peer_reviewed</lds50><oa>free_for_read</oa><woscitedreferencessubscribed>false</woscitedreferencessubscribed><citedby>FETCH-LOGICAL-c609t-7271533a06f734e25441b0d1ad5eeb22c975d0f838e9dbd5573d5543b016f1b33</citedby></display><links><openurl>$$Topenurl_article</openurl><openurlfulltext>$$Topenurlfull_article</openurlfulltext><thumbnail>$$Tsyndetics_thumb_exl</thumbnail><link.rule.ids>314,776,780,1877,27901,27902</link.rule.ids><backlink>$$Uhttp://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=14914971$$DView record in Pascal Francis$$Hfree_for_read</backlink></links><search><creatorcontrib>Paananen, Timo</creatorcontrib><creatorcontrib>Heinänen, Kyösti</creatorcontrib><creatorcontrib>Härkki, Jouko</creatorcontrib><title>Degradation of Iron Oxide Caused by Alumina during Reduction from Magnetite</title><title>ISIJ International</title><addtitle>ISIJ Int.</addtitle><description>The degradation mechanism of iron oxides caused by alumina during reduction from magnetite has been studied. The experiments were carried out by reducing briquettes containing various mixtures of commercial magnetite fines and Al2O3 in a CO/CO2 atmosphere at 950°C in thermo-gravimetric equipment. Following reduction, samples were examined using optical microscopy, SEM-EDS and XRD. The diffusion of Al cations into the magnetite during reduction induces swelling and cracking of the briquettes. The composition of the magnetite phase approaches the composition of hercynite during reduction. Assuming the spinel structure is that of hercynite, reduction to non-stoichiometric wüstite (Fe0.88O) causes an expansion of over 16%. This transformation causes high tension forces in the magnetite/hercynite phase in the vicinity of the interface with the wüstite which presumably account for the breakdown of the structure during the reduction.</description><subject>alumina</subject><subject>Applied sciences</subject><subject>degradation</subject><subject>degradation mechanism</subject><subject>Direct reduction</subject><subject>Exact sciences and technology</subject><subject>hercynite</subject><subject>Iron and steel making</subject><subject>magnetite</subject><subject>Metals. Metallurgy</subject><subject>Production of metals</subject><subject>reduction</subject><subject>wüstite</subject><issn>0915-1559</issn><issn>1347-5460</issn><fulltext>true</fulltext><rsrctype>article</rsrctype><creationdate>2003</creationdate><recordtype>article</recordtype><recordid>eNplkE9LxDAUxIMouKjfIRe9dU2apGmOsv5bVETRc3hNXtdIN9WkBf321l3Rg_CYufzmDQwhlLN5KZQ6DTm8hjhgijCEPkI3l2KujN4hMy6kLpSs2C6ZMcNVwZUy--Qo59AwVspaCi5m5OYcVwn8Jk77li7T5PcfwSNdwJjR0-aTnnXjOkSgfkwhrugj-tFtAm3q1_QOVhGHMOAh2Wuhy3j04wfk-fLiaXFd3N5fLRdnt4WrmBkKXWquhABWtVpILJWUvGGeg1eITVk6o5VnbS1qNL7xSmkxiRQN41XLGyEOyMn271vq30fMg12H7LDrIGI_ZlvqWpSykhNYb0GX-pwTtvYthTWkT8uZ_R7Q_hvQSmGnAafo8U8HZAddmyC6kP_y0kyn-cQ9bLnXPMAKfwFIQ3Ad_i_gpjabkq1MXb-se4FkMYovRR-UaA</recordid><startdate>20030101</startdate><enddate>20030101</enddate><creator>Paananen, Timo</creator><creator>Heinänen, Kyösti</creator><creator>Härkki, Jouko</creator><general>The Iron and Steel Institute of Japan</general><general>Iron and Steel Institute of Japan</general><scope>IQODW</scope><scope>AAYXX</scope><scope>CITATION</scope><scope>8BQ</scope><scope>8FD</scope><scope>JG9</scope></search><sort><creationdate>20030101</creationdate><title>Degradation of Iron Oxide Caused by Alumina during Reduction from Magnetite</title><author>Paananen, Timo ; Heinänen, Kyösti ; Härkki, Jouko</author></sort><facets><frbrtype>5</frbrtype><frbrgroupid>cdi_FETCH-LOGICAL-c609t-7271533a06f734e25441b0d1ad5eeb22c975d0f838e9dbd5573d5543b016f1b33</frbrgroupid><rsrctype>articles</rsrctype><prefilter>articles</prefilter><language>eng</language><creationdate>2003</creationdate><topic>alumina</topic><topic>Applied sciences</topic><topic>degradation</topic><topic>degradation mechanism</topic><topic>Direct reduction</topic><topic>Exact sciences and technology</topic><topic>hercynite</topic><topic>Iron and steel making</topic><topic>magnetite</topic><topic>Metals. Metallurgy</topic><topic>Production of metals</topic><topic>reduction</topic><topic>wüstite</topic><toplevel>peer_reviewed</toplevel><toplevel>online_resources</toplevel><creatorcontrib>Paananen, Timo</creatorcontrib><creatorcontrib>Heinänen, Kyösti</creatorcontrib><creatorcontrib>Härkki, Jouko</creatorcontrib><collection>Pascal-Francis</collection><collection>CrossRef</collection><collection>METADEX</collection><collection>Technology Research Database</collection><collection>Materials Research Database</collection><jtitle>ISIJ International</jtitle></facets><delivery><delcategory>Remote Search Resource</delcategory><fulltext>fulltext</fulltext></delivery><addata><au>Paananen, Timo</au><au>Heinänen, Kyösti</au><au>Härkki, Jouko</au><format>journal</format><genre>article</genre><ristype>JOUR</ristype><atitle>Degradation of Iron Oxide Caused by Alumina during Reduction from Magnetite</atitle><jtitle>ISIJ International</jtitle><addtitle>ISIJ Int.</addtitle><date>2003-01-01</date><risdate>2003</risdate><volume>43</volume><issue>5</issue><spage>597</spage><epage>605</epage><pages>597-605</pages><issn>0915-1559</issn><eissn>1347-5460</eissn><abstract>The degradation mechanism of iron oxides caused by alumina during reduction from magnetite has been studied. The experiments were carried out by reducing briquettes containing various mixtures of commercial magnetite fines and Al2O3 in a CO/CO2 atmosphere at 950°C in thermo-gravimetric equipment. Following reduction, samples were examined using optical microscopy, SEM-EDS and XRD. The diffusion of Al cations into the magnetite during reduction induces swelling and cracking of the briquettes. The composition of the magnetite phase approaches the composition of hercynite during reduction. Assuming the spinel structure is that of hercynite, reduction to non-stoichiometric wüstite (Fe0.88O) causes an expansion of over 16%. This transformation causes high tension forces in the magnetite/hercynite phase in the vicinity of the interface with the wüstite which presumably account for the breakdown of the structure during the reduction.</abstract><cop>Tokyo</cop><pub>The Iron and Steel Institute of Japan</pub><doi>10.2355/isijinternational.43.597</doi><tpages>9</tpages><oa>free_for_read</oa></addata></record> |
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| subjects | alumina Applied sciences degradation degradation mechanism Direct reduction Exact sciences and technology hercynite Iron and steel making magnetite Metals. Metallurgy Production of metals reduction wüstite |
| title | Degradation of Iron Oxide Caused by Alumina during Reduction from Magnetite |
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