Microwave reduction of a nickeliferous laterite ore

Samouhos, M; Taxiarchou, M; Hutcheon, R; Devlin, E

dc.contributor.author	Samouhos, M	en
dc.contributor.author	Taxiarchou, M	en
dc.contributor.author	Hutcheon, R	en
dc.contributor.author	Devlin, E	en
dc.date.accessioned	2014-03-01T02:11:25Z
dc.date.available	2014-03-01T02:11:25Z
dc.date.issued	2012	en
dc.identifier.issn	08926875	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/29897
dc.subject	Extractive metallurgy	en
dc.subject	Iron ores	en
dc.subject	Pyrometallurgy	en
dc.subject	Reduction	en
dc.subject.other	Alternative energy source	en
dc.subject.other	Carbon content	en
dc.subject.other	Cavity perturbation method	en
dc.subject.other	Complex dielectric constant	en
dc.subject.other	Convective heat transfer	en
dc.subject.other	Heating time	en
dc.subject.other	Improving efficiency	en
dc.subject.other	Infrared thermal-camera	en
dc.subject.other	Metallic iron	en
dc.subject.other	Microstructural homogeneity	en
dc.subject.other	Microwave furnace	en
dc.subject.other	Microwave-heating systems	en
dc.subject.other	Mineral processing	en
dc.subject.other	Nickeliferous laterite	en
dc.subject.other	Optical pyrometers	en
dc.subject.other	Reduction degree	en
dc.subject.other	Slow heating	en
dc.subject.other	Small samples	en
dc.subject.other	Ssbauer spectroscopies	en
dc.subject.other	Temperature range	en
dc.subject.other	Thermal inhomogeneity	en
dc.subject.other	Variable power	en
dc.subject.other	Carbon	en
dc.subject.other	Carbothermal reduction	en
dc.subject.other	Dielectric materials	en
dc.subject.other	Extractive metallurgy	en
dc.subject.other	Heating	en
dc.subject.other	Hematite	en
dc.subject.other	Iron ore reduction	en
dc.subject.other	Iron ores	en
dc.subject.other	Microwave ovens	en
dc.subject.other	Microwaves	en
dc.subject.other	Pyrometallurgy	en
dc.subject.other	Reduction	en
dc.subject.other	Scanning electron microscopy	en
dc.subject.other	Soils	en
dc.title	Microwave reduction of a nickeliferous laterite ore	en
heal.type	journalArticle	en
heal.identifier.primary	10.1016/j.mineng.2012.04.005	en
heal.identifier.secondary	http://dx.doi.org/10.1016/j.mineng.2012.04.005	en
heal.publicationDate	2012	en
heal.abstract	The use of microwave radiation as an alternative energy source in mineral processing and extractive metallurgy has been studied since the initial work of Worner at the Univ. of Wollongong in 1986. Microwaves deliver heat directly to the interior of a sample, avoiding the usual slow heating mechanisms of thermal and convective heat transfer. Furthermore, the depth to which the microwaves penetrate and the amount of heat deposited at depth is dependant on the complex dielectric constant of the material which means that by careful choice of materials, a microwave heating system can deliver heat to specific chosen materials, while much reducing the heating of others, such as thermal insulation and oven walls, and thus improving efficiency. In the current study, the carbothermic reduction of a hematitic nickeliferous laterite was investigated, both by large-scale microwave oven experiments, and by measuring the complex dielectric constant (real (′) and imaginary (″) permittivities) of small samples at 2.45 GHz over the temperature range 5-980 °C, using the cavity perturbation method. The microwave oven heating behavior of the laterite-lignite mixture was explored using a 2.45 GHz ThermWave 1.3, variable power, microwave furnace, fitted with an optical pyrometer and an infrared thermal camera. The carbothermic reduction of laterite (i.e. the reduction of hematite contained in laterite) was attempted, and the effect of heating time, power, carbon content and sample mass was studied in detail. Using twice the stoichiometric carbon content (i.e. double the amount of carbon required to fully reduce the hematite to metallic iron), about 70% reduction degree was achieved at temperatures somewhat above 900 °C. The use of scanning electron microscopy and Mössbauer spectroscopy gave evidence of a lack of microstructural homogeneity in the reduced samples and the presence of phases which are not stable in the same temperature ranges, indicating some thermal inhomogeneity. © 2012 Elsevier Ltd. All rights reserved.	en
heal.journalName	Minerals Engineering	en
dc.identifier.doi	10.1016/j.mineng.2012.04.005	en
dc.identifier.volume	34	en
dc.identifier.spage	19	en
dc.identifier.epage	29	en