Process Integration Solutions for Water Networks in Integrated Steel Making Plants

Process Integration capabilities of promoting the internal recycling and reuse of material and energy streams allow reaching the goals of sustainable processing. Water is one of the main industrial resource which use has to be optimised to decrease freshwater intake and wastewater blowdown. Preliminary studies on the feasibility of different options are developed through Process Modelling and Simulation to predict process behaviour before plants conversion. The paper presents the approach to the problem of water reuse for an Italian integrated steelmaking plant. Application to a real case has been developed, related to reuse of continuous casting wastewater blowdown in basic oxygen steelmaking gas washing system. Process Modelling with main assumptions and results are described. The option is promising, as it involves a reduction of fresh water drawing up to 33 %, with changes in blowdown features of 2 % for pH value increase and 13 % for electrical conductivity reduction at constant global mass balance.