Enhancement of energy and resource efficiency and reduction of greenhouse gas emissions in the iron and steel industry and the zinc industry

The production and recycling network of the iron and steel industry as well as the zinc industry consumes enormous amounts of primary resources and energy, especially ores, coke and coal and secondary resources like steel scrap. Further, significant loads of by-products like dusts, sludges and slags accrue. Besides power producers and the traffic sector the network is also one of the main emission sources of greenhouse gases like CO₂. Rising coal, coke, and energy prices as well as deposition fees and CO₂-emmission certificate prices lead - together with changing legal requirements - to an increasing relevance of the resource and energy efficiency and greenhouse gas emissions for the actors in the described network. In recent years therefore many efforts have been carried out to increase resource and energy efficiency, to reduce costs for the disposal of by-products and to decrease the CO ₂-emissions. In the outcome nowadays many of the accruing by-products are circulated within the individual sites. This may be optimal for the single company but can also lead to higher energy demands, higher costs or a decrease of productivity for other actors in the considered network. The presentation therefore describes an approach in which not every actor in the network is optimised individually but an optimisation of the whole network is carried out. For this we consider an integrated steel works, a secondary steel producer, two established recycling companies as well as a hydrometallurgic zinc smelter. The approach comprises a combination of flowsheet simulation tools to achieve a detailed and problem adequate model of the physical and chemical process of the different plants and material and energy flow simulation tools to link the resulting input and output streams of the single plants of the network. This method allows to analyse techno-economic effects of changes in mass and energy flows without field tests in the participating companies. By using methods from operations research it is possible to optimise different aspects like the mass of accruing by products, required energy and emissions of green house gasses etc. for the whole network. Game theoretic methods will be applied for the allocation of the estimated cooperation costs and benefits.