The Role of Metallic Iron in Low Temperature Carbothermic Reduction of MnO: Phase Chemistry and Thermodynamic Analysis

Manganese ore reduction is quite complex at intermediate reaction temperatures of 1100–1400 °C due to the formation of liquid oxide and/or alloy phases in varying phase proportions and distributions. Evidence in the literature shows that MnO reduction rates are higher for manganese ores of higher ir...

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Autor principal:	Theresa Coetsee
Formato:	article
Lenguaje:	EN
Publicado:	MDPI AG 2021
Materias:	ferromanganese manganese ore alloy reduction phase chemistry Mineralogy QE351-399.2
Acceso en línea:	https://doaj.org/article/31a70f80064f4889a177854f83f624c9
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spelling	oai:doaj.org-article:31a70f80064f4889a177854f83f624c92021-11-25T18:26:15ZThe Role of Metallic Iron in Low Temperature Carbothermic Reduction of MnO: Phase Chemistry and Thermodynamic Analysis10.3390/min111112052075-163Xhttps://doaj.org/article/31a70f80064f4889a177854f83f624c92021-10-01T00:00:00Zhttps://www.mdpi.com/2075-163X/11/11/1205https://doaj.org/toc/2075-163XManganese ore reduction is quite complex at intermediate reaction temperatures of 1100–1400 °C due to the formation of liquid oxide and/or alloy phases in varying phase proportions and distributions. Evidence in the literature shows that MnO reduction rates are higher for manganese ores of higher iron mineral content. This is due to a lowering of the manganese activity in the presence of iron and carbon in the alloy. Consequently, the minimum required temperature for carbothermic reduction of MnO is lowered. The simplification of the complex ore reduction system is achieved by reacting pure MnO with carbon instead of using gangue-containing ore. The effect of variation in the %C in the alloy product has not been well quantified in previous works. Here the complete alloy phase analyses are used to clarify the role of metallic iron added to MnO-Fe-C compressed pellets reacted at 1100 and 1200 °C. The phase chemistry analyses show that the alloy compositions follow a polynomial curve in %Mn vs. %C plots, with alloy phase compositions formed internal to the MnO particles containing lower %Mn (<50%) and lower %C (<6%) vs. alloy phase compositions formed external to the MnO particles at 60–71% Mn and 6–10% C. Most of the Mn-Fe-C alloy areas internal to the MnO particles are liquid at 1200 °C. Thermodynamic analysis shows that the low-temperature reduction (1200 °C) of MnO in the presence of metallic iron is possibly due to lowered Mn activity in the product alloy Mn-Fe-C alloy and reduction via CO.Theresa CoetseeMDPI AGarticleferromanganesemanganese orealloyreductionphase chemistryMineralogyQE351-399.2ENMinerals, Vol 11, Iss 1205, p 1205 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	ferromanganese manganese ore alloy reduction phase chemistry Mineralogy QE351-399.2
spellingShingle	ferromanganese manganese ore alloy reduction phase chemistry Mineralogy QE351-399.2 Theresa Coetsee The Role of Metallic Iron in Low Temperature Carbothermic Reduction of MnO: Phase Chemistry and Thermodynamic Analysis
description	Manganese ore reduction is quite complex at intermediate reaction temperatures of 1100–1400 °C due to the formation of liquid oxide and/or alloy phases in varying phase proportions and distributions. Evidence in the literature shows that MnO reduction rates are higher for manganese ores of higher iron mineral content. This is due to a lowering of the manganese activity in the presence of iron and carbon in the alloy. Consequently, the minimum required temperature for carbothermic reduction of MnO is lowered. The simplification of the complex ore reduction system is achieved by reacting pure MnO with carbon instead of using gangue-containing ore. The effect of variation in the %C in the alloy product has not been well quantified in previous works. Here the complete alloy phase analyses are used to clarify the role of metallic iron added to MnO-Fe-C compressed pellets reacted at 1100 and 1200 °C. The phase chemistry analyses show that the alloy compositions follow a polynomial curve in %Mn vs. %C plots, with alloy phase compositions formed internal to the MnO particles containing lower %Mn (<50%) and lower %C (<6%) vs. alloy phase compositions formed external to the MnO particles at 60–71% Mn and 6–10% C. Most of the Mn-Fe-C alloy areas internal to the MnO particles are liquid at 1200 °C. Thermodynamic analysis shows that the low-temperature reduction (1200 °C) of MnO in the presence of metallic iron is possibly due to lowered Mn activity in the product alloy Mn-Fe-C alloy and reduction via CO.
format	article
author	Theresa Coetsee
author_facet	Theresa Coetsee
author_sort	Theresa Coetsee
title	The Role of Metallic Iron in Low Temperature Carbothermic Reduction of MnO: Phase Chemistry and Thermodynamic Analysis
title_short	The Role of Metallic Iron in Low Temperature Carbothermic Reduction of MnO: Phase Chemistry and Thermodynamic Analysis
title_full	The Role of Metallic Iron in Low Temperature Carbothermic Reduction of MnO: Phase Chemistry and Thermodynamic Analysis
title_fullStr	The Role of Metallic Iron in Low Temperature Carbothermic Reduction of MnO: Phase Chemistry and Thermodynamic Analysis
title_full_unstemmed	The Role of Metallic Iron in Low Temperature Carbothermic Reduction of MnO: Phase Chemistry and Thermodynamic Analysis
title_sort	role of metallic iron in low temperature carbothermic reduction of mno: phase chemistry and thermodynamic analysis
publisher	MDPI AG
publishDate	2021
url	https://doaj.org/article/31a70f80064f4889a177854f83f624c9
work_keys_str_mv	AT theresacoetsee theroleofmetallicironinlowtemperaturecarbothermicreductionofmnophasechemistryandthermodynamicanalysis AT theresacoetsee roleofmetallicironinlowtemperaturecarbothermicreductionofmnophasechemistryandthermodynamicanalysis
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The Role of Metallic Iron in Low Temperature Carbothermic Reduction of MnO: Phase Chemistry and Thermodynamic Analysis

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