Assessment of Treatment Configurations through Process Simulations to Improve Basic Oxygen Furnace Slag Reuse

Abstract

The European steel sector aims at improving its material efficiency by increasing the by-products recycling rate. This can lead to approach the ambitious “zero-waste” goal, by minimising the need for landfilling, saving raw materials, reducing emissions and contributing to improve the economic sustainability of the production cycle. The steelmaking process produce several by-products: slags are the main one and can be used to make different products, including cement, fertilisers and asphalt. This paper presents a work aiming at obtaining reusable fractions from the Basic Oxygen Furnace slag. Two Aspen Plus®-based models were developed and exploited: a model of the slag treatments to make sensitivity analyses, providing information about different slag treatment configurations, particularly on different magnetic separation solutions, and a model computing the pellet composition according to the different inputs. Other models, developed through reMIND® software, are material flow superstructures that implemented results from the treatment model. They allowed assessing the best route for internal or external reuse of the slag fraction, taking into account process, environmental and economic impacts and making optimization assessment. They are able to identify the slag quality that is more suitable for the reuse. The developed models can provide significant improvements based on economic and environmental sustainability (e.g. increase of by-products recycling, reduction of slag recovering in the internal quarry, reduction of treatment costs, etc.) compared to the current use at ILVA Steelworks.