Novel applications of microwaves in the metallurgical processing of a nickel-ferrous laterite ore and an aluminum industry waste

Abstract

Microwave radiation is a relatively new source of energy in the pyrometallurgical process. In this study, the application of microwaves in the carbothermic reductive roasting of a nickeliferous hematitic laterite ore and a red mud are investigated. The effective microwave heating (at temperatures above 900°C) of the aforementioned materials is attainable due to the relatively high values of their imaginary permittivity (ϵ)- In both two cases, the reduction of the included hematite was attempted, and the reduction degree was calculated as a function of: (a) the heating time and (b) the supplied microwave power. The mechanism of Fe+3 to Fe0 conversion was investigated using Mössbaurer spectroscopy revealing the formation of magnetite, fayalite and nano-structured metallic iron. Finally, it should be noted that that the gaseous products of the microwave pyrometallurgical process were analyzed using a mass spectroscopic technique, which is an important novelty.