Optimisation of a centralised recycling system for steel plant by-products, a logistics perspective

This paper focuses on the optimisation of a recovery strategy for waste materials and thereby improved material efficiency in the iron and steel industry. A joint venture between four Nordic steel plants is considered in order to recycle materials otherwise mainly put to landfill, i.e. dusts and sludges from the steel production processes. Process integration (PI) was used to investigate the possibilities for recovering the materials by developing a system optimisation model of the steel plants and integrating a dedicated material upgrading process in the system. This work aims to develop a model suitable for analysing and finding a logistic solution needed to achieve a common recycling system by studying material supply, required material storage, shipping system and shipping frequency. The developed optimisation model is presented, using a case study of the steel production plants with the dedicated upgrading process and the logistics system. The prospect for shipping materials from the steel production sites to the material upgrading process site as well as the material supply to the upgrading unit is essential in the system analysis. A mathematical optimisation model based on mixed-integer linear programming (MILP) for the common system is presented. The integration of the dedicated material upgrading process show a system in balance regarding the materials generated and processed in the upgrading unit. Generated material amounts suitable for the upgrading process can be fully recovered thereby decreasing the landfilled amounts from the four steel production sites. (C) 2013 Elsevier B.V. All rights reserved.