Reduction Behaviour of Self-reducing Blends of In-plant Fines in Inert Atmosphere

• Published in: ISIJ International Vol. 55; no. 10; pp. 2082 - 2089
• Main Authors: Ahmed, Hesham Mohamed, Persson, Amanda, Ökvist, Lena Sundqvist, Björkman, Bo
• Format: Journal Article
• Language: English
• Published: The Iron and Steel Institute of Japan 01.01.2015
• Subjects: BF dust and sludge; BOF dust and sludge; heating microscope; mass spectroscopy; Process Metallurgy; Processmetallurgi; self-reducing mixtures; thermodynamics; thermogravimetery; waste materials recycling
• ISSN: 0915-1559; 1347-5460; 1347-5460
• DOI: 10.2355/isijinternational.ISIJINT-2015-182

Large amount of dust and sludge recovered during cleaning of iron and steel making process gases are annually put on landfill or intermediate storage. These by-products have high contents of iron (Fe) and carbon (C) that potentially could be utilized in the steel industry. However, due to the presence of impurity compounds as well as the unsuitable physical properties, these by-products cannot be recycled directly. The main objective of the present study is to investigate the possibilities to recover the valuable components Fe and C in these by-products and thereby decrease the need of landfills at the steel plants as well as reduce the consumption of virgin materials, including fossil coal, and reduce CO2 emissions. A recycling route has been investigated by means of laboratory trials and FactSage thermodynamic modeling. Four different blends of BF and BOF dusts and sludges are prepared in predetermined ratios. Reduction behavior of each blend is studied using TG/DTA/QMS and in-situ high temperature X-ray diffraction. High temperature physical properties like softening, swelling and melting are also investigated by means of heating microscope. The obtained results indicate the feasibility of both minimizing the impurity elements as well as recovering of valuable components.