Microwave reduction of copper(II) oxide and malachite concentrate

Samouhos, M; Hutcheon, R; Paspaliaris, I

dc.contributor.author	Samouhos, M	en
dc.contributor.author	Hutcheon, R	en
dc.contributor.author	Paspaliaris, I	en
dc.date.accessioned	2014-03-01T01:36:12Z
dc.date.available	2014-03-01T01:36:12Z
dc.date.issued	2011	en
dc.identifier.issn	0892-6875	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/21278
dc.subject	Extractive metallurgy	en
dc.subject	Non-metallic ores	en
dc.subject	Pyrometallurgy	en
dc.subject	Reduction	en
dc.subject.classification	Engineering, Chemical	en
dc.subject.classification	Mineralogy	en
dc.subject.classification	Mining & Mineral Processing	en
dc.subject.other	Carbon content	en
dc.subject.other	Carbon source	en
dc.subject.other	Carbothermic reduction	en
dc.subject.other	Cavity perturbation method	en
dc.subject.other	Copper (ii)	en
dc.subject.other	Dielectric constants	en
dc.subject.other	Energy source	en
dc.subject.other	Experimental procedure	en
dc.subject.other	Graphite powder	en
dc.subject.other	High temperature	en
dc.subject.other	Maximum temperature	en
dc.subject.other	Metallic oxides	en
dc.subject.other	Microwave absorption	en
dc.subject.other	Microwave radiations	en
dc.subject.other	Mineral processing	en
dc.subject.other	Power supply	en
dc.subject.other	Rapid-heating	en
dc.subject.other	Reduction degree	en
dc.subject.other	Reduction rate	en
dc.subject.other	Reduction reaction	en
dc.subject.other	Temperature range	en
dc.subject.other	Time-periods	en
dc.subject.other	Absorption	en
dc.subject.other	Calcination	en
dc.subject.other	Carbothermal reduction	en
dc.subject.other	Copper oxides	en
dc.subject.other	Copper smelting	en
dc.subject.other	Extractive metallurgy	en
dc.subject.other	Froth flotation	en
dc.subject.other	Graphite	en
dc.subject.other	Heating	en
dc.subject.other	Lignite	en
dc.subject.other	Metallic compounds	en
dc.subject.other	Metals	en
dc.subject.other	Microwaves	en
dc.subject.other	Mixtures	en
dc.subject.other	Ores	en
dc.subject.other	Perturbation techniques	en
dc.subject.other	Pyrometallurgy	en
dc.subject.other	Reducing agents	en
dc.subject.other	Carbonate minerals	en
dc.title	Microwave reduction of copper(II) oxide and malachite concentrate	en
heal.type	journalArticle	en
heal.identifier.primary	10.1016/j.mineng.2011.03.026	en
heal.identifier.secondary	http://dx.doi.org/10.1016/j.mineng.2011.03.026	en
heal.language	English	en
heal.publicationDate	2011	en
heal.abstract	The use of microwave radiation as an energy source in mineral processing and extractive metallurgy has demonstrated both the instantaneous generation of heat by microwaves in a number of compounds and minerals, and the achievement of high temperatures for an efficient time period enable the heating and reduction of metallic oxides and ores. In the present study, the carbothermic reduction of copper oxide (CuO) and one malachite [Cu2CO3(OH)(2)] concentrate were investigated. To explore feasibility, the dielectric constants [real (epsilon') and imaginary (epsilon '') permittivities] of both materials were measured at the frequencies of 2.45 GHz and 912 MHz, in the temperature range from 25 to 800 degrees C using the cavity perturbation method. The high epsilon '' values (between 1.9 and 36.3) observed in the case of CuO suggest strong microwave absorption, while the malachite concentrate values (between 0.1 and 0.4) indicate limited microwave absorption. Experiments showed the microwave heating rate of CuO was considerably higher than that of the malachite concentrate. The carbothermic reduction of CuO oxide was examined, and the effect of power supply, carbon source, carbon content and granularity of the reducing agent on the reduction rate was studied in detail. Using an 800W power supply, and with addition of lignite as a reducing agent (with carbon content two times stoichiometric), almost complete reduction of 10 g of CuO was achieved in 4 min. The carbothermic reduction of one malachite concentrate was attempted with the same experimental procedure, but the reaction was not possible using only lignite as the reducing agent, since the poor microwave absorption of malachite concentrate-lignite mixture produced a maximum temperature of 200 degrees C. This difficulty was overcome by the addition of 5% by weight of graphite powder to the mixture. The rapid heating of the malachite concentrate-lignite-graphite mixture (800 degrees C after 2 min) resulted in sequential malachite calcination and CuO reduction reactions. After 8 min at a power supply of 800W, the reduction degree of CuO produced by the calcination of malachite was about 90%. (C) 2011 Elsevier Ltd. All rights reserved.	en
heal.publisher	PERGAMON-ELSEVIER SCIENCE LTD	en
heal.journalName	Minerals Engineering	en
dc.identifier.doi	10.1016/j.mineng.2011.03.026	en
dc.identifier.isi	ISI:000292580800026	en
dc.identifier.volume	24	en
dc.identifier.issue	8	en
dc.identifier.spage	903	en
dc.identifier.epage	913	en