Abstract
Electric arc furnace dust (EAFD) is a significant secondary resource harbouring valuable metallic constituents like zinc, iron and at the same time, it is also a hazardous material as it releases toxic heavy metals like cadmium, lead and chromium to the environment. One potential way to utilise EAFD is to reduce it in the form of self-reducing EAFD–coal composite pellet and subsequently charge it to blast furnace for iron recovery while heavy metal will pass through slag to the cement industry. This investigation reports the reduction behaviour of EAFD–coal composite pellets in tube furnaces at various carbon levels. Temperature of the furnace varied between 1000°C and 1300°C and residence time from 5 to 20 min. The transverse cross section of the reduced pellets showed three layers with slag layer at the surface, followed by slag entrapped iron layer, and finally a partially reduced powdery central core. The central core increased with increase in coal content of the pellet, responsible lower extent of reduction. Temperature had little effect on reducing the dimension of the central core. A layer of iron and slag enveloping the core caused gas and pressure build-up at the core, which was thought to hinder the gasification reaction and lessen the amount of reduction. Temperature measurements did not show large temperature difference between surface and centre reflecting a less significant effect of heat transfer. It was concluded that EAFD–coal composite pellet could best be reduced at C/O ratio of 1. The reduced pellets are thoroughly characterised by scanning electron microscope/energy dispersive X-ray spectroscopy and X-ray diffraction analysis.
Get full access to this article
View all access options for this article.